We get accused a lot of being anti-diesel. In reality, most of us love driving them. Paying for them is another issue. VW has just announced pricing on the new 2010 Golf VI, and the diesel premium is…premium. As in $4500. Strictly speaking, that investment also buys you a slightly lowered suspension (cost to VW: $0), and a slightly better audio unit (cost to VW: $50?). Here are the numbers: 2 door gas (2.5, 170 hp, EPA: 22/30) starts at $17,490; 2 door TDI (2.0, 140 hp, EPA: 30/41) starts at $21,990. Annual fuel cost savings are $362 for the TDI. Maintenance and repair costs favor the gas engine. Zero to sixty is similar with either model, with the gas (7.8 seconds) edging out the diesel (8.6 seconds) by a nose. The question we have is why not bring over VW’s excellent new 1.6 liter TDI engine, which makes 105 hp, and can easily top 50 mpg. Do diesel drivers prefer lowered suspensions and high(er) performance, or maximum mileage and a lower price?
Like the other German makers, they seem to be missing a trick here. Maybe gas prices are too low again now, but I certainly can see a market for a 1.6 TDI or for that matter a BMW 118d at the right price.
Because most Americans (even diesel lovers) wouldn’t consider a 1.6 liter anything as a “real” engine. I’d be pleased as punch with the 1.6 TDi along with the torque it brings, not to mention the fuel economy…but, if it came at a huge premium (as does the 2.9 TDi), then it becomes a non-starter. Sure, they’ll advertise the 41 MPG, but as shown, the average fuel savings would be (let’s be gracious) around $400. It would take 11 years to recover the cost differential! Another case of VW shooting itself in the foot, then quickly reloading the gun…
Because most Americans (even diesel lovers) wouldn’t consider a 1.6 liter anything as a “real” engine. I’d be pleased as punch with the 1.6 TDi along with the torque it brings, not to mention the fuel economy…but, if it came at a huge premium (as does the 2.0 TDi), then it becomes a non-starter. Sure, they’ll advertise the 41 MPG, but as shown, the average fuel savings would be (let’s be gracious) around $400. It would take 11 years to recover the cost differential! Another case of VW shooting itself in the foot, then quickly reloading the gun…
Obviously they should be selling both, but my bet is they aren’t making any real money on the TDI’s in the states yet. If that guess is correct then the TDI’s, kinda like the GTI I guess, are on lots to help sell Jettas.
I guess the question that matters is, “Could VW sell a 1.6L TDI cheaper than they push the current 2.0L?)
If that guess is correct then the TDI’s, kinda like the GTI I guess, are on lots to help sell Jettas.
I wonder about that – in my neighborhood there are 3 GTIs for every one Golf. I’d be interested to see the actual sales ratio. I checked, but it seems that while VW release sales by modle it doesn’t break down sales between Golf/GTI and Jetta/GLI.
One rare positive consequence of the higher CAFE standards is that some makers, and especially the German LUXURY car makers, will be FORCED to bring in their smaller as well as larger diesels, in order to achieve their CAFE MPG increases.
In the past, they preferred paying the few millions in penalties, but under the new rules, this is NOT an option.
Somebody like VW may be able to avoid this because it has high-volume efficient VW models countering the thirstier Audis, but Merc and BMW can’t do the same.
The suspension and other mods baffle me to be honest. For a while we had two VWs here at home and I swapped the 205/70 tires off the gasser onto the normally 195/70 shod TDI and the results shocked me. MPG dropped from ~50 MPG to about 42 MPG overnight. Needless to say the narrow 195s went back on the TDI asap.
VW can sell Diesel here in the USA IF and ONLY IF they can demonstrate big MPG numbers. the 1.6 can do that. So can the old 1.9 TDI. They seem to have lost the plot with the 2.0 though.
I will challenge your “Maintenance and repair costs favor the gas engine” statement however. Compared to VW’s 1.8T and 2.5 gasoline mills the TDIs have proven to be dirt cheap to own and operate. High reliability has been the TDI’s record to date. Only the old 2.0 I-4 gasoline engine (or the old VW aircooled flat four!) can compare in terms of reliability and cheap repair costs. The only pricey job on a VW TDI is the injection pump and timely filter changes will keep it running well for decades. That filter is a $30 part and a 5 minute job to DIY with three tools every shade-tree wrencher owns already.
–chuck
Never understood some people’s fascination with longer molecules.
At $22k, a person must be out of his mind to choose a 140hp TDI over a 249hp Sonata V6.
Perplexing, especially as VW seems to have no problem selling every one, yet BMW puts $4500 on the hood and still can’t move them.
As I’ve said before, VW has a niche and I think they are still just selling TDI’s to that club. It will be very interesting to see if they can expand that in any real way.
One thing that ALL manufacturers seem to be doing very carefully is bringing diesels that perform exactly as well as the gas models. There is still a lot of baggage left from the US 80’s diesel disaster, and I think everyone, even VW, is terrified of bringing over anything that might be seen as sluggish, noisy, or in any way “worse” than a gas version of the vehicle. Even if that means the mileage gains aren’t stellar.
The 1.6 TDI is probably insignificantly less expensive to manufacture. Parts count will be the same and it will still need the same exhaust system aftertreatment. But they can probably have an easier time selling the 2.0 TDI because of the North American desire for horsepower, and it would be too expensive to EPA-certify both powertrains (with both available transmissions).
As for the price premium … The quoted cost savings per year are based on average drivers, but at least around here, most folks who drive TDI are doing so because they put on high annual mileage (I was in that category until the recession hit).
At today’s local fuel prices based on the Shell station around the corner (92.7 cents/litre regular unleaded, 88.9 cents/litre diesel) and based on a real-world-expectation 5.5 L/100 km for the TDI (that’s on the high side of what my previous-TDI-engine Jetta uses) and 9.0 L/100 km for the gas engine, and C$5000 to account for the currency, the TDI will go ahead of the game on cash flow in about 140,000 km. Until the recession, I was doing that every two years.
Diesel lovers prefer low-end torque, coupled with great fuel economy.
A VW customer that prefers a lower suspension, and better performance will always opt for the GTI.
I opted for the GTI, but the TDI was still a very nice car.
That Diesel premium is indeed insane.
The pricing for the Golf GTI and the Golf GTD here in Germany is different, however. They differ marginally, given the price level of almost 30,000 Euros for both (c.f. http://cc5.volkswagen.de/cc5/configurator/fs_base.aspx?context=default&app=ICC-DE ).
Diesel Fanboys:
Diesels are much more expensive to design, produce, and service. That is fact.
I like diesels, but they do not make economic sense when TCO is taken into account. Cleaning up the emissions has lowered efficiency and increased cost and complexity.
but petrol (gas) cars have ignition and VANOS or double VANOS (BMW). and those are not cheap, too. I think it really depends on what sound and elasticity one wants. The diesel motor lasts longer, it’s the components that don’t (pump,turbo, injectors)
Most of you are missing the mark here.
Diesel enthusiasts tend to log on very high miles. I would say that most drive north of 20k per year, and about 40% are north of 30k (judging by what I see at the auctions).
I would also add that in another two years, the Germans may be patting themselves on the back instead of shaking their heads. But with the dollar… who knows.
My sister has owned 4 or 5 VW diesels going back to an 81 Rabbit diesel. As they have grown in size, a 50 mpg car seems to be down to a 40 mpg car, but the flip side is a lot more power. She remains very happy and a loyal VW diesel person. The last 2 or 3 have been TDIs, going back, I believe, to a 95 Passat.
For whatever reason, even VW has struggled to keep a regular diesel supply here in the states. There have been times when sis kept a car longer than she wanted to while waiting for diesels to be reintroduced in the US.
After her experience, I would definitely consider a diesel, but the price premium is brutal. This is true in VWs and in Ford Excursions.
We get accused a lot of being anti-diesel. In reality, most of us love driving them. Paying for them is another issue. VW has just announced pricing on the new 2010 Golf VI, and the diesel premium is…premium. As in $4500.
One of the things that bugs me about diesel advocacy is thus: the ills of hybrid cars (supposed reliability, increased cost and complexity) also exist with diesels, yet this rarely gets play. The inherent conservatism in automobile fans plays a big role here.
Diesel cars are no longer appreciably more reliable, from a holistic point of view, than gas cars. Hybrids are proving to be as reliable, or more reliable, than gas cars. The “diesel advantage” that came from a massively over-engineered block doesn’t really exist, not now that everyone seems to have sorted out fuel injection and modern metallurgy.
Diesels are not mechanically simple: there’s a lot of tight-tolerance, high-cost, high-complexity components in these cars, in addition to the mess of electronics in every car. This ain’t your granddad’s Mercedes 300D.
I’m not saying diesels are bad, only that a lot of the virtues vis a vis normal cars aren’t really significant, or are outright detriments.
On a recent 2 week vacation in Scotland with my wife and another couple we rented a nearly new (400 miles) beautiful dark blue Peugot 308 SW equipped with a 1.6 HDi engine and a manual transmission.
http://www.peugeot.com/en/products/cars/peugeot-308-sw.aspx
First it was amazing that this fairly small station wagon could swallow the four of us and all our luggage in relative comfort. The glass roof (the entire roof) and very supportive seats front and rear were terrific. But what we continued to be blown away with was the ability of that small diesel engine to so willingly pull us over 1000 miles of both city and highway driving, all the while delivering mileage in the mid/high 30’s. We even saw low 40’s over the course of 2 days of mostly highway driving.
Is there a place in our world for green diesel engines, certainly. Just wished the manufacturers could figure out how to get them to us for something less than a $1000… perhaps Hyundai should turn their engineers loose on this :-)
If I drove alot of miles, then I’d consider one. A diesel may last for quite a long time, but I’m afraid the surrounding VW will not. I would consider a Jetta wagon TDI, if I were to consider any VAG product. Torque, excellent mileage (more for the lack of needing to stop for refueling), and a comfortable ride from a tidy package is appealing…all for the price of your average, and smaller, FWD crossover.
Finally, the price premium is diminished a little with a tax credit (at least for the 09 Jetta TDI).
Steven Lang-
I would imagine that the manufacturers would like to get past selling to “diesel enthusiasts” and start selling them to everyone. This distinction doesn’t exist in the rest of the world, only in the US where it has required an effort to hunt down the few available cars, find fuel, etc. and some folks even go so far as to brew their own! Rarity breeds this type of enthusiasm.
There many issues to deal with before diesel is nothing more than a check-box option in the US, but I believe that is the ultimate goal.
@ Niedermeyer:
The question we have is why not bring over VW’s excellent new 1.6 liter TDI engine, which makes 105 hp, and can easily top 50 mpg.
Probably because a Cocker Spaniel could outrun the thing…:)
I’m just not sold on diesels, and I don’t think America will be either, unless a) fuel goes up 300% in price, and b) diesel is a lot cheaper than gas. Those are the conditions that made diesel such a hit in Europe; our market just works differently.
And don’t even get me started on the BMW 335d…who the hell thought a $45,000 economy car was a good idea? A 3-series is a trophy car, one you roll up in front of your buddies and brag about how fast it is. Somehow, “Yeah, this baby will get 35 miles per gallon” doesn’t quite do it…
I can’t speak for anyone else, but I personaly don’t just look at the initial price premium and then divide by the annual fuel savings when making the gas vs. diesel decision. It’s not all about dollars and cents anymore. Some of us just want to feel a little bit less piggish about our fossil fuel consumption. I love my 98 Jeep Wrangler 4.0, but these days feel like a bit of a prick driving it, at 16 mpg or whatever. If they would put the 3.0 turbo diesel in the new Wrangler, it would be about enough to assuage my guilt, and I would consider buying one.
I really don’t think I am the only one who feels this way. Spend a bit more to help out the environment. Why not?
Steven Lang :
October 2nd, 2009 at 3:58 pm
Most of you are missing the mark here.
Diesel enthusiasts tend to log on very high miles. I would say that most drive north of 20k per year, and about 40% are north of 30k (judging by what I see at the auctions).
True, but let’s be honest: drivers who log that kind of mileage are a minority. Most drivers drive 12-15,000 miles a year, so the cost savings of diesel just don’t add up. I think that’s why they have such a limited market here.
WAY back in the day, though, I used to sell advertising over a five-state territory, racking up well over 40,000 miles a year, and if I’d had something like a Mercedes Bluetec diesel, it’d have been a Godsend.
Here in Canada, the upcharge for diesel is $2300, so I’d assume that you’re getting some more bling along with your diesel for your $4500 price. And even if lowered suspension doesn’t cost Volkswagen anything, it’s something that any enthusiastic driver would pay some extra money for. No other manufacturer that I know of offers free sport suspension either.
Figuring the annual fuel savings using today’s price may not be accurate. If I buy a new car I’m going to keep it 5-7 years (or more if I’m enjoying life) and I’d assume that over those five plus years fuel is going to get more expensive. I recall paying $1.5 per litre of premium not too long ago, so I expect that I’ll see that price again in the not-too-distant future.
Looking at this ‘your way’ the upcharge for a GTI over a Golf is ridiculous because mostly you’re getting a Golf with sport suspension, bigger rims and a turbo motor.
What becomes of this $4k “diesel premium” once you factor in depreciation? Assuming one traded in his diesel after several years for another one.
Around here TDIs are the only cars to depreciate less than Civics and Corollas, so that $4k diesel premium mostly comes back you in the end.
I would also add that in another two years, the Germans may be patting themselves on the back instead of shaking their heads. But with the dollar… who knows.
That’s why they are building a factory in Chattanooga – no matter what happens to the dollar they will be fine. Same with BMW and Mercedes – no reason they can’t expand if it becomes necessary.
Am I correct that all X5s sold worldwide are built in South Carolina?
A 3-series is a trophy car, one you roll up in front of your buddies and brag about how fast it is. Somehow, “Yeah, this baby will get 35 miles per gallon” doesn’t quite do it…
What part of torque do you not understand?
335d = 425 lb-ft
M3 = 295 lb-ft
Call me crazy, but I would be willing to pay a premium because in my own humble opinion I just love the way a diesel drives. I don’t understand that people demand a price premium is objectively justified. I would consider it paying for a feeling, a driving sensation; not for “more expensive components” or “better fuel economy”.
jmo :
October 2nd, 2009 at 5:23 pm
What part of torque do you not understand?
335d = 425 lb-ft
M3 = 295 lb-ft
Torque is great – it’ll get you off the line quickly – but after 3500 rpm in the 335d, the show’s over. The gas version is just getting started. That’s why the gas version will beat the diesel by about a second to 60. It’s not even close.
Don’t get me wrong. The 335d engine is brilliant, but if you’re buying a performance sedan, which are you going to spend your hard-earned bucks on: the model that costs more and goes slower, or the faster one that costs less? In this application, I’d argue that fuel economy is probably the least of a buyer’s worries, as long as the car gets reasonable mileage (which the gas 335 does – 17/26).
a remapped E92 335d beat the E92 M3 on a closed circuit by a fraction but beat it. the diesel had around 334 bhp and close 450lb-ft. One thing is clear, though. The sound and elasticity of a petrol engine is what makes it more beautiful. but mark, the 2.0TDi beats the 1.4 TSI (both 168 hp)in a 0-60 sprint.
Torque is great – it’ll get you off the line quickly – but after 3500 rpm in the 335d, the show’s over. The gas version is just getting started.
Um…the 335d redlines at 5000 rpm .
Do you do most of your driving sprinting from 0-60?
425 lb-ft at 1750 rpm is much more usable in the real world than 414bhp at 8000 rpm.
Great – you can get a compact car that gets 32/41. Lots of other options in that category already. There’s one that gets 50+ mpg already for a small premium over the Jetta.
What about a minivan that carries seven that gets 32/41? Or a 5 passenger wagon with 40 cu ft luggage capacity that gets 32/41 and can tow 2000 lbs?
Is it is just me or do there seem to be a relatively small number of choices in vehicles to buy? Can VW import the Sharan already and stop putting all its effort into the most crowded market segments??
What part of torque do you not understand?
I personally don’t understand the fixation on torque, when the vehicles aren’t any faster because of it.
According to Edmunds, a 335i gets to 60 1.1 seconds earlier than a 335d. The fact that the 335i has 125 fewer lb/ft of torque doesn’t matter — the gas motor is still quicker.
Meanwhile, the diesel is consuming a fuel that requires more oil to produce, creating an mpg difference which is largely illusory when accounting for the amount of oil actually being consumed. It isn’t reasonable to directly compare gasoline MPG with diesel MPG, but that doesn’t seem to stop the fans from doing it.
Yeah, and the soot of diesel particles is bad even with less CO2 than the gas engines produce. In Germany diesel is normally 15-20% cheaper (except summer 2008 when it got more expensive than gas, even in France and Spain). but they pay some 150-200€ more (yearly) because of pollution. (120€ vs. 320€ for Merc C220). In France gas is 25% over diesel (and no “diesel” tax. Only CO2 matters there. That’s why 70-80% of new cars in those countries are tractors. Germany is not so diesel-oriented. My question is: how much is gas and diesel in the US and what pollution/emission laws do u have over there?
The only question we should be asking is whether the cars will sell at that price or not. I have a feeling they will.
Everyone missed one big difference in the actual purchase price. The gas version can be purchased for dealer invoice, the diesel version is MSRP at minimum. Obviously the diesel’s mileage can’t come close to making up the initial cost difference making the diesel a non starter IMO. It’s a comparable scenario with the Fusion Hybrid about $6k more than the 2.5L. These vehicles are both completely overpriced for what they offer in comparison to their gas models and other competitors. There is no way to justify purchasing them based on MPG. At $22k about the very last vehicle I would buy is a Golf TDI, too many nicer vehicles for the same or less money.
Wow, feel the love in this place.
On most Canadian highways the fastest thing on the highway is a TDI . Cruising at 130/140 kmh’s while getting pretty good mileage . Also not having to stop every two hours makes most other cars fall way behind at the end of the travel day.
Also in Regina , diesel is 40 cents a US gallon cheaper.
I see TDI’s as a viable alternative unless low HP’s numbers challenge your street cred.
“…High reliability has been the TDI’s record to date.”
CR VW diesel engine reliability is a mixed bag.
00,01 worse than average, 02 somewhat worse than average, 03,04 average, 05 better than average, 06 somewhat better than average. Rated average used car buys 00 – 05, somewhat better than average 06.
Pch101 :
Meanwhile, the diesel is consuming a fuel that requires more oil to produce, creating an mpg difference which is largely illusory when accounting for the amount of oil actually being consumed. It isn’t reasonable to directly compare gasoline MPG with diesel MPG, but that doesn’t seem to stop the fans from doing it.
Do you have any technical documents you could refer me to ? From what I have read , Gas and diesel are cracked at different temperatures in the stack out of a the same barrel of oil. Diesel is done in one step , gasoline is done in more sub steps.
@ kevnsd
perhaps Hyundai should turn their engineers loose on this
They already have. We get the diesel models in Australia and they seem to be selling no problems. It think the 1.6L and 2L TDi engines are available in quite a few Hyundai cars in Australia.
@ Freedmike
And don’t even get me started on the BMW 335d…who the hell thought a $45,000 economy car was a good idea? ….. Somehow, “Yeah, this baby will get 35 miles per gallon” doesn’t quite do it…
You’ve used that one before eh? You might as well ask why does anyone buy ANY luxury item? Come up with the answer and I know you can head up Saatchi or earn $millions/year on the business speaking circuit.
(Don’t tell anyone else yet if you do know).
@ Pch101 (also @ Dorian666)
Meanwhile, the diesel is consuming a fuel that requires more oil to produce, creating an mpg difference which is largely illusory when accounting for the amount of oil actually being consumed.
I respect your comments, but you make it seem like refining is as simple as poor-in some Crude at the top, fiddle some knobs and get fuel out the bottom. In reality there is a diminishing return on cracking the longer chains. Refiners tune (within limits) for a $$$ return at the lowest input cost (crude and process energy).
I am continually amazed by the number of people who wouldn’t think twice about spending several thousand dollars on an upgraded trim package, or a DVD navigation system they seldom use, but suddenly when it comes to diesel or hybrid it’s all about dollars and cents. I’d bet that if you put together all of the Escalade drivers in the world, you would find that they were subjected to less unwanted cost benefit analysis from other people for overpaying for their Chevy with better seats and worse wheels, than just one average VW TDI or Toyota Prius driver. Really, I’m far more offended that VW chooses to call their Golf a Rabbit in the US, than I am offended by the cost of their diesel option. Diesel drivers are paying for torque at low revs, and a long cruising range, and arguably a lower carbon footprint, far more than they are making an investment in a technology that has a guaranteed payoff. If it were all about dollars and cents, and nothing more, there wouldn’t be an unusual or interesting car on the road.
strange that (at least in Europe) BMW diesel and gas are same price. But the non-premium car manufacturers all charge a premuim for their diesel engines (VW, Peugeot, Toyota,… well, everybody except Merc and BMW). I think it’s curious…
Vehicle pricing is not set by the cost of the components. Even so the rather vague stab at component cost in this article is pretty poor. Usually any off standard component, eg lowered suspension, will cost more, because it costs the supplier more to tool up for it, and the OEM more to develop it.
A lowered suspension will often contain the following – new springs (obviously), shock calibration, and bump stops. Possibly new sta bars. Each will have a development cost and a tooling cost, even if there is no hit on variable cost.
It also may need a different alignment setting – more complexity in plant, and possibly shims to set camber.
I realise that in TTAC-world all of this stuff is mere details, but it’s the details that get ya.
Diesel gas isn’t at every station here in metro Chicago. Having to remember what station sells it or not finding a station with it could be a reason they’re not bought.
Too bad; I thought the diesel premium (at least on the Jetta) was around $2000. Now it’s a tougher decision. Or not.
Given that it brings more revenue to the government in the form of higher per gallon tax, one can only be in awe that Obama hasn’t already mandated that by 2010 fully 50% of road cars must be diesel!
@PCH101
Huh? Back when I took chemistry, diesel cracked out below petrol. It took less energy to refine crude to diesel and diesel was more energy dense (more btu/gallon) than petrol. Has neu chemistry done for the discipline what neu math did to my kids? And, man, do I miss my little stretch of PCH 101!
@gslippy, Without analyzing the Jetta model content, it appears that the premium there is indeed only about $2000. (And as someone else pointed out, in Canada the Golf TDI premium is in the same range.)
Interestingly for 2010 Canada has also switched to VW’s global model nomenclature, including Golf GTI (no longer just “GTI”) and Golf Wagon (no longer Jetta Wagon). Also the trim lines are the usual sportline, comfortline and highline; meanwhile, US Jetta models have S, SE and SEL.
The direct comparison of engine torque between diesel and gas cars misses an important point: the gear ratio. This makes the torque at the wheel (the one that matters) nearly identical. And this is what may be termed as the theoretical torque at full boost. Then you have to factor the turbo lag. In most of diesels they appear to perform with some kind of slow motion thinking between pressing the gas pedal and the engine transient response is appalling. The higher the output (high boost), the worse they are. This is mostly noticeable in town driving which cancels its key advantage: where the engine is most efficient is also very unsatisfying to drive. Diesel engines work in very stressed (thermal and mechanical) environments and therefore high durability is only in our memories. Also their efficiency (mpg) has being going down because manufacturers have been reducing the compression ratio in order to improve the drivability. So in the end it only makes sense for those who drive really a lot and, because of the tax subsidies to the fuel is some countries. But I acknowledge that there is a great benefit of diesel motoring: that smell of truck driver one gets at ever fill up. Very professional looking and priceless. Particularly in a high end automobile.
For $2k the diesel would be a consideration at $4,500 it’s off the table.
Do you have any technical documents you could refer me to ?
You don’t need them. This is basic chemistry.
When viewed in terms of weight, gas and diesel have about the same energy content. That is to say, a pound/ kilo of diesel has about the same energy content as does a pound/ kilo of gasoline.
But the specific gravity of diesel is about 15% higher than it is for gasoline. When comparing them when using a liquid measure such as gallons or liters, a given unit of diesel has more energy content than a unit of gasoline. Diesel is a heavier fuel, presumably because it has been refined less.
In other words, a pound of diesel takes up less space than does a pound of gas, which means fewer gallons of it. That doesn’t make diesel better or worse, it just makes it more compact.
The problem is that the average dieselhead doesn’t know squat about chemistry, but was raised by car commercials to equate “mpg” with “efficiency” while failing to understand that mpg and l/100 km only work as efficiency measures if you are comparing the same kinds of fuels across comparable vehicles.
If our gas stations sold us our fuel by the pound, then there would be less confusion about the concept of “efficiency.” But because we were raised to buy it in gallons or liters, there is a lot of ignorance about what it actually means.
you make it seem like refining is as simple as poor-in some Crude at the top, fiddle some knobs and get fuel out the bottom.
That’s a real stretch. For one, I didn’t discuss refining in this context. For another, it’s completely irrelevant to what I am talking about.
Again, the problem is with the fact that the average person talks about fuel using liquid measures. The diesel fans misinterpret what this means and then distort it beyond recognition.
Diesels are slightly more efficient than gas motors because they run at higher compression. But most of the mpg difference between gasoline and diesel comes from this issue of this difference in energy content of the fuels when compared using liquid measures, while some of it often comes from the fact that the diesel motors almost always have turbos while the gas motors usually don’t. Again, if we bought fuel by weight, instead of by liquid, this wouldn’t be an issue.
I looked up the 15 cars and 10 trucks on Autoblog that made the short (?) list for COTY and TOTY.
The 335d was there, and deservedly so, and I ranked it No. 2 of 15 (Prius III being no. 1 in my book), but I was outraged that among the 10 insignificant POS trucks, the outstanding BMW X5 D was missing!
Motorweek tested it and its ACTUAL average MPG (Average!! Not Hwy) was 27++ MPG, higher even than the EPA HIGHWAY number (26) for this 7 seat behemoth!
As a former TDI owner (we used to have two, but the mileage between the cars was so close it was getting expensive to maintain two on the same service schedule. My wife’s Jetta remains) who chipped and upgraded the suspension on his car, I can tell you that 1.) there is a market out there for Diesels with at least sporting pretensions and 2.) there is a thriving community out there for people who tinker on their TDIs to improve both mileage and performance (I’m looking at you, TDIClub.com)
While VW has built a following with the TDI, one of the drawbacks has always been (at least for us 2-door Golf fans) that to get a 2-door Golf TDI you had to do without niceties such as a sunroof, bigger wheels, a sport suspension, etc. The cars were the base model GL(or what passes for base model with VW, my car had power windows, Monsoon sound system, A/C, etc.). If you wanted any of the creature comforts that help a long commute pass by you had to go with the 4-door or buy a Jetta. Too bad the mileage isn’t quite what it was with my ’03, which was EPA rated at 42/49, and which I regularly exceeded, even after having the chip installed.
The flipside of what PCH101 is saying is that a gallon of diesel emits about 15% more carbon than a gallon of gasoline.
By pricing the diesel at the premium VW did it will remain a niche market vehicle. Nice car but no value for the price. BTW, comparing the diesel cost to an Escalade is pure ridiculousness. People don’t buy Escalades for value they buy them for prestige. The luxury market is an entirely different one from those that would consider the VW diesel offerings based on value. If a buyer was in the luxury market a VW diesel would not be a consideration.
@ Pch101
it’s completely irrelevant to what I am talking about
We end up with diesel because of the nature of the refining process. So a statement about diesel thus;
a fuel that requires more oil to produce, creating an mpg difference which is largely illusory when accounting for the amount of oil actually being consumed
is meaningless, because there is limited control of “the amount of oil” that is “consumed”. Diesel is a product of the process.
if we bought fuel by weight, instead of by liquid, this wouldn’t be an issue.
Why? Crude is not processed or priced by energy content or weight; you end up with a volume of fuel to sell. The price of the fuel is structured in such a way as to deliver maximum return for the refiner by volume.
For the consumer, $3/gal for gasoline goes 26miles in a BMW 335i highway, while $3/gal for diesel goes 36miles in a BMW 335d highway. (Or what-ever the price is, set by the refiner).
Specific gravity, mass or energy content doesn’t interest the refiner or consumer.
There would be less confusion about fuel effectiveness if we all used g/CO2 per Km travelled as is increasingly common in Europe.
Diesel is a product of the process.
So is gasoline. A refined barrel of oil produces all sorts of products, from asphalt to jet fuel.
Specific gravity, mass or energy content don’t interest the refiner.
But they interest the chemist, and we are allegedly discussing the chemistry of fuel consumption.
Trying to claim that diesel is better because it has more energy density per gallon would be akin to arguing that chocolate cake is healthier than broccoli because the cake has more energy (calories) per serving. Of course, that would be a ridiculous statement to make, but that apparently doesn’t prevent diesel fans from saying it.
The unit of measure is just a function of packaging. We buy fuel by the gallon because somebody decided to package it like that. That’s a function of convenience, but tells us nothing at all about efficiency.
jmo :
October 2nd, 2009 at 6:38 pm
Torque is great – it’ll get you off the line quickly – but after 3500 rpm in the 335d, the show’s over. The gas version is just getting started.
Um…the 335d redlines at 5000 rpm .
…and the one I drove was Game Over at 3500, maybe 4000. You can rev it to 5000, but all you’re doing at that point is producing noise.
Meanwhile, the gas version makes usable power all the way to the redline (somewhere around 7,000 rpm, as I recall), and makes an exhaust note that’s pure Pavarotti.
The gas engine is a better cboice for a high-performance sedan, period, unless the buyer is fixated on economy. But how many people who buy high-performance sedans are fixated on MPG? Not many.
Not saying BMW hasn’t made a great diesel here – they have – but the gas version is heads and shoulders better. That’s why the diesel isn’t selling.
For the consumer, $3/gal for gasoline goes 26miles in a BMW 335i highway, while $3/gal for diesel goes 36miles in a BMW 335d highway. (Or what-ever the price is, set by the refiner).
Specific gravity, mass or energy content doesn’t interest the refiner or consumer.
There would be less confusion about fuel effectiveness if we all used g/CO2 per Km travelled as is increasingly common in Europe.
These paragraphs contradict each other. Diesel would look about 15% worse if we used gCO2/km, since diesel has more carbon in a gallon than gasoline does, being more dense. The EPA is pretty clear about this. Diesel 10.1 kgCO2/gallon, gasoline 8.8 kgCO2/gallon.
Using gCO2/km (or mi) would be more accurate for the person who cares about CO2 emissions directly, but less accurate for the average driver, who as you notes care about “how far can I go on a gallon, and for how much?” Actually, people probably care more about “how far can I got on a full tank?” or “how far can I go for a certain amount of money?
Diesel’s 15% higher MPG are more useful for average consumers who care about how far they’re going on a gallon. You just shouldn’t use them when talking about CO2 emissions and global warming. Use the proper units for the proper problem.
Dorian666 :
October 2nd, 2009 at 9:37 pm
Wow, feel the love in this place.
On most Canadian highways the fastest thing on the highway is a TDI. Also in Regina , diesel is 40 cents a US gallon cheaper.
Well, as they say, what’s good for Saskatchewan is not necessarily good for everyone else… :)
Here in Colorado, gas and diesel are almost identical price-wise, with gas being slightly less expensive. This is why diesels haven’t caught on in the States.
And if a TDI is the hot rod of choice in Canada, I feel sorry for you guys.
johnthacker :
October 3rd, 2009 at 10:50 am
Diesel’s 15% higher MPG are more useful for average consumers who care about how far they’re going on a gallon.
The problem: people who buy 3-series BMWs aren’t average consumers. They’re performance-oriented drivers. They aren’t buying a more expensive diesel car unless gas becomes radically more expensive, period.
Average consumers won’t either. Why buy a $24,000 Jetta TDI when a far cheaper Corolla or Civic get more-than-respectable mileage and cost a lot less?
Unless we as a society are going to commit to European-level fuel taxation, diesel ain’t the answer in America.
Diesel’s 15% higher MPG are more useful for average consumers who care about how far they’re going on a gallon.
But it is ignorant to use MPG in the context of discussing efficiency, as is so often the case in these internet wars waged by the diesel pundits.
For whatever reason, they are fixated on MPG as an efficiency measure. They are wrong, but difficult to educate.
@Pete Moran:
You’ve used that one before eh? You might as well ask why does anyone buy ANY luxury item? Come up with the answer and I know you can head up Saatchi or earn $millions/year on the business speaking circuit.
(Don’t tell anyone else yet if you do know).
Hey, I don’t advertise myself as a marketing expert, but it’s common sense: by and large, people who buy luxury cars don’t buy them because they get great fuel economy. Do you disagree?
I know BMW’s trying to sell economy in their line, but frankly, my local dealers have ordered a few diesels and haven’t been able to move them. The closest one to me still has the same 335d they got back in the spring. What does that tell you?
Now, if gas prices go up radically, it’ll be a different story. But for now, I think it’s safe to say that aside from a small but devoted slice of the market, diesels don’t sell to luxury car buyers.
Actually, I take that back. What the average consumer wants to know is a combination of “how much will it cost (or how many gallons do I need) to go this distance that I’m going to go,” which is a gallons/100mi question, as well as “how far can I go on a full tank,” which is a traditional MPG question.”
Gallons/100mi looks very different to people than MPG, though. Going from 10 to 11.1 to 12.5 to 14.3 to 16.6 to 20 to 25 to 33 to 50 to 100 MPG saves the same amount of gallons per 100mi each jump. (Counting from 10 down to 1.)
Pch101: “Again, if we bought fuel by weight, instead of by liquid, this wouldn’t be an issue.”
Despite the evolution of the argument into what may be considered semantics, this statement has made sense out of the issue.
I was once amazed when a friend told me that the first stage of the Saturn V (moon) rocket used kerosene and liquid oxygen instead of liquid hydrogen and LOX — the energy density of kerosene is much greater than liquid hydrogen (if, which they had used, would have resulted in a first stage much larger than feasible.)
Since when have eco-cars like Hybrids been about saving money? The financial ownership equation of a Prius looks much the same.
Maybe VW are aiming for those who want to use less fuel but also like to drive?
I always liked diesels (grew up with one in the late 70s) and have always wanted one, but it would be for towing, or in a Jeep for off-road use. Otherwise unless it’s purchase price is about the same as a gas powered car, I’d pass on it.
I was once amazed when a friend told me that the first stage of the Saturn V (moon) rocket used kerosene and liquid oxygen instead of liquid hydrogen and LOX — the energy density of kerosene is much greater than liquid hydrogen (if, which they had used, would have resulted in a first stage much larger than feasible.)
I can believe that. For stuff that flies, the energy density really is an issue, because lower density requires larger equipment to travel a given distance. Adding a larger fuel tank to a rocket isn’t all that easy, obviously.
Jet fuel has a specific gravity very much like that of diesel. For an airplane, this is important, given all of the space limitations of airplane design.
For a car, it doesn’t matter so much. Cars can travel reasonable ranges on standard-sized tanks of diesel, gasoline, or for that matter, ethanol.
From a macro standpoint, the smart thing to do would be to prioritize the high density fuels for the equipment that needs them most, so that we don’t run out of the more critical fuels or squander them on the wrong equipment.
@ johnthacker
Diesel would look about 15% worse if we used gCO2/km, since diesel has more carbon in a gallon than gasoline does, being more dense.
The opposite is true. Please consult ComCar as an example.
For Range choose “Any”, for Make choose “Volkswagen”, for Doors choose “5” and then Engine Size choose “2 – 2.5”.
@ Pch101
For whatever reason, they are fixated on MPG as an efficiency measure. They are wrong, but difficult to educate.
A ridiculous statement.
Less diesel is used to go the same distance in equivalent cars.
BMW 335i 17/26MPG vs BMW 335d 23/36MPG, a 35%/38% advantage.
By volume (energy density) diesel has ~10% more energy than gasoline.
By mass (specific energy) diesel has ~7% more energy than gasoline.
Diesel is ~18% more dense than gasoline.
The 335d 6M produces 173g/CO2 per Km, while the 335i 6M produces 218g/CO2 per Km, or a 26% lower advantage in carbon “consumption” from the input crude.
Diesel engines are significant more energy effective, making use of the already refiner priced fuel more efficiently.
Where it possible to change the refining ratio, we would be using LESS crude oil overall by using MORE diesel.
Less diesel is used to go the same distance in equivalent cars.
If you refined a barrel of oil to produce another 100 gallons of diesel, you’d lose about 115 gallons of gasoline.
This is what diesel fans refuse to understand. The tradeoff between the two fuels is not equal. They are different fuels.
If you skew toward diesel, you lose more gas. If you skew towards gas, you don’t lose as much diesel.
It shouldn’t about MPG of a specific fuel type, but how about many miles can be powered by a barrel of oil. It is wrong to use MPG as an efficiency measure when comparing across fuel types.
Our refineries are designed to produce a given ratio of gas and diesel. If we were smart, we would stick to that ratio, so as to avoid supply shortages.
The US already orients its refining toward maximizing gasoline production. The US uses enormous quantities of diesel, but limits most of that usage to heavy trucks, industry and agriculture.
If the US were to shift dramatically to more diesel passenger cars, the price of diesel fuel would go up, not just in the US but in Europe. Europe has gone nuts with diesel, and as a result, they are exporting gas that they can’t use, while importing diesel from the US because there are few sources for the ULSD that they require, and it is not possible for their refineries to serve their current demand ratios. A mass diesel conversion would create particular problems during an economic recovery, because economic growth tends to place more demands on diesel, given the diversity of equipment that uses it.
The fixation on one fuel type over another is frankly stupid beyond belief. Advocating diesel over gasoline is akin to arguing that we should only eat chicken wings, and throw away the breasts. If we are going to be resource efficient, then we should use each fuel in the appropriate fashion, and then try to reduce our consumption of both.
Someone above mentioned invoice vs MSRP. Very good point. Just a quick look at edmunds and invoice on the 2010 Golf is about $700 less than MSRP. Probably more with a few options. So add another $700 to the cost.
Resale should be considered. However, if you’re making payments, that’s a lot of extra scratch to shell out a month. Getting it back years down the road is hard to remember. Plus, you always want it earlier (invest, buy something else,etc).
I’m now in Germany for the next year and as everyone knows, most things here are diesel. I always thought diesel had an aura to it in the US…it was unique. And I do like the scoot they have, plus seeing 40+mpg on the computer is nice. However, being here for awhile now, its losing its luster to me. I had dreams of maybe buying the 123d BMW at some point. I should still drive it. 300ish lbft of torque sounds great. And great mileage. But seeing (and hearing) all these diesel cars day after day has really killed it for me. The cars idle like garbage. They sound terrible. When they accelerate, they still sound terrible. There is no exhaust note, just diesel clatter. And at cruise, again, no noise (of the good or bad kind). And driving a diesel isn’t too rewarding. There’s little enjoyment out of blasting to redline, grabbing the next gear, and doing it again. They don’t like to rev, and they lose power at the top. Bah. Great for a cheap commuter, bad for everything else.
Seeing a 5 series roll by, but hearing the diesel clatter really drops the car’s status in my eye. It just seems way less luxurious to me. And I tell ya, when a gas powered model drives by, under open throttle, my head now turns every time, particularly a V8 or a Porsche. The sound is superb. It SOUNDS like a quality car.
And hearing a gas car open up on the autobahn is pure music. Its the way cars should be, my opinion.
Anyone know where the ’10 US-market Golf will be made?
The morons at VW USA decided to stick us with that ridiculous 2.5 iron 5-banger (along with the TDI) again. Base price of the gasser is almost $1200 higher than ’09!
I’d be OK with that if instead of that heavy, lumpy, low-mpg five, they offered the 1.4TSI gas engine that puts out 160ps. But no, us Yanks are too fat and stupid to know anything about engines. I don’t think that engine is even offered anywhere else, probably because nobody would buy it.
@Jerome10,
The great thing about living in Germany is that you have tons of choice, both diesel and non-diesel, and you can choose the one that best matches your criteria.
On this side of the pond, we have much more limited engine choices, though we do get lower prices yo make up for that.
A relative of mine had a 2002 Jetta TDI that went thru two turbos under warranty, he traded on a 2008 jetta TDI and the motor recently suffered catastrophic failure of a main bearing. He likes to do his own oil changes and VW canada says his warranty is viod, and is quoting him $21,000 Canadian loonies to replace the motor. I love my gas powered Hondas!
Between the diesel price premium and the 5 cyl gas lump VW offers as the only choices in the US for the Golf and Jetta they have done a fine job of positioning themselves out of the volume segment these cars compete in. I can’t imagine what else they could possibly do to make themselves less competitive. Talk about completely clueless, VW takes the cake.
@mtymsi: Talk about completely clueless, VW takes the cake.
If you want to assign blame, it should largely be laid at the door of VWoA rather than Wolfsburg, which is still doing rather well from a global point of view.
Very true. I’m not saying that diesels are a good match for the majority of consumers. But it is a very good alternative for a substantial portion of today’s market.
Having a half dozen to a dozen cars available with the diesel is a good beginning. If the costs become more competitive (or gas and diesel become equal in cost), it will definitely become a mainstream technology.
For now nearly every car in today’s market is losing money. I don’t see that changing until at least 2011.
rozenman : A relative of mine …traded on a 2008 jetta TDI and the motor recently suffered catastrophic failure of a main bearing. He likes to do his own oil changes and VW canada says his warranty is viod…
This would not happen in the US as long as the oil was VW approved, done at suggested service intervals, and receipts are kept. I do not know Canadian law, but if what you say is the case, your relative was rather stupid not to understand the rules of the game.
@ Pch101
If you refined a barrel of oil to produce another 100 gallons of diesel, you’d lose about 115 gallons of gasoline.
Yet in a typical case the same car with an equivalent diesel engine would then use ~30% less diesel! Less crude oil!
If you skew toward diesel (in refinement), you lose more gas. If you skew towards gas, you don’t lose as much diesel.
If that were POSSIBLE, that argument would make sense. You can control the “skew” to an extent before your return on energy input (cost of production) starts to diminish. The price for the two fuels reflects that now.
It is wrong to use MPG as an efficiency measure when comparing across fuel types.
The refiner has already priced the resulting fuel. If the per gallon cost is similar (as it is at the moment), then MPG tells you all you need to know. The decision about how “energy valueable” or “crude oil valueable” the fuel is has already been made during refinement. You see it as a PRICE.
If the US were to shift dramatically to more diesel passenger cars, the price of diesel fuel would go up
A valid concern. It would have to approach ~30% dearer than gasoline to reach equality in terms of consumption spend. Even then, LESS crude would be being used.
Advocating diesel over gasoline is akin to arguing that we should only eat chicken wings, and throw away the breasts.
That argument is a nonsense. No-one would be throwing anything away. The price for the two fuels reflect the best possible (current) return for the refiner. If the useage pattern changes and the refiner can react there might be more diesel available or the price might go up (or both).
If that happens, the MPG figures still roughly reflect the efficieny; the consumer then works it out in their pocket book.
The concept doesn’t seem to escape people in Europe.
Yet in a typical case the same car with an equivalent diesel engine would then use ~30% less diesel!
A really bad habit of the diesel fans is their consistent tendency to compare dissimilar cars when making the MPG claims.
An example is the 335i vs. 335d citation made above. All things being equal, fuel consumption is a function of power output. The 335i produces more power, and is obviously a much quicker car. Ignoring the performance difference leads to illegitimate comparisons; the diesel is clearly not on par with the gas car in terms of the performance attributes that determine relative fuel consumption.
There is no 30-35% difference in the amount of petroleum being consumed, when the big picture and performance differences are taken into account. You get differences like these only by comparing faster gas cars with slower diesels, and by ignoring the issue of specific gravity.
You can control the “skew” to an extent before your return on energy input (cost of production) starts to diminish.
Modifying refineries is expensive. Refiners are not inclined to invest heavily into expanding or changing capacity, because their margins are too low to make it worth their while.
So the end result is that a massive change in US diesel consumption would inevitably increase retail prices, both here and in Europe where dependency on US diesel fuel imports is an issue. Not a smart idea.
The concept doesn’t seem to escape people in Europe.
Taxes on diesel in Europe have been much lower than the taxes on gasoline, due to efforts by their trucking lobby to keep their fuel cheaper. The end result has been to create an incentive for European consumers to buy diesel cars.
Such incentives don’t exist in the US and probably never will, as we are unlikely to have such high levels of gas taxes to inspire a market response. Since there is clearly little demand otherwise, we don’t face the same issues.
No-one would be throwing anything away.
If we were to pay attention to the internet diesel fanatics, we would stop using gas altogether. To anyone who knows anything about oil refining, that is of course a ridiculous objective.
If you want to assign blame, it should largely be laid at the door of VWoA rather than Wolfsburg, which is still doing rather well from a global point of view.
I’d like to point out the VWoA is largely beholden to VWAG, and it’s VWAG who has been terminally incapable of understanding the North American market. Largely, I might add, because they keep trying to treat it as a second-world version of Europe.
Except for the last two years, this has been a bad thing, as they’ve been effectively shut out of a 330-million consumer market.
@ Pch101
The 335i produces more power
13% more power than the 335d. (265hp vs 300hp).
Raise the power of the 335d by 13%, and (other things being equal), you would still have ~17%/23% MPG advantage, while CO2 output would be close to 195 g/CO2 per Km vs 218.
At the “same” power, that’s 12% less of your precious specific gravity carbon atoms going down the tailpipe! The very definition of efficiency, because those carbon atoms were available in the crude beforehand.
Overall, less crude oil is consumed, not more.
The difficulty is how do you make more diesel and the answer is you can’t to a large extent. The price reflects that reality, but if we were serious about energy/fuel EFFICIENCY we’d use more diesel.
@ Pch101
Actually, I’m told that in refining terms, the various sulfur treatment add significantly to the upstream energy input to create diesel, I’d not considered. European Brent has an advantage there as to it’s “sweetness”. The US has less and less West Texas available, with import choices being higher sulfur content rated (sour).
Process energy for diesel is therefore higher in the USA.
I have an (unfortunately private) 2008 ELF report (in conjunction with PSA Group) looking at pursuit of diesel in the US, suggesting that Advanced Gasoline Hybrids are both more cost and oil effective anyway – no surprise.
“Diesel” like technologies such as gasoline direct injection should further close the engine efficiency gap, so gasoline effectiveness should rise.
In cost effectiveness terms (for oil saving) ranked most to less; full hybrid, then advanced gasoline (with DI), then advanced diesel which was a surprise.
In cost effectiveness terms (for CO2 saving) ranked most to less; full hybrid, advanced diesel and then advanced gasoline.
I do believe that the lower CO2 output of diesel is related to the amount of carbon emitted as soot particulates, which (while not a greenhouse gas) is a problem itself.
In the words of the immortal LJK Setright, a diesel engine is like a gasoline engine with the torque peak shaved off. The so-called flat torque “curve” misses the peak of a gasoline engine. Diesels don’t rev, they rattle, have high weight to keep the blocks together under the groaning stress of diesel compression ignition, require turbocharging for the merest modicum of “performance”, and their exhaust makes my eyelids puff up. Will no-one relieve me of these monstrosities?
@frozenman:
I smell an operator error here. Two different cars with (likely) oil related mechanical issues with the common denominator of an owner who likes to do his own oil changes. I sold my Golf TDI with 160k on the odometer. I had to clean out my intake manifold once but the turbo was fine. The new owner recently replaced the turbo as a performance upgrade. My wife’s Jetta TDI has 170k on the original turbo. Again, the intake needed to be cleaned out, but that is a known issue with the EGR (well, known to everyone but VWoA). I did almost all the maintenance on both cars (except the timing belts and a clutch upgrade after I chipped my Golf) in my driveway.
TDI turbos rarely go bad but the engines are somewhat sensitive to what oil is being usd in them.
And don’t even get me started on the BMW 335d…who the hell thought a $45,000 economy car was a good idea? A 3-series is a trophy car, one you roll up in front of your buddies and brag about how fast it is. Somehow, “Yeah, this baby will get 35 miles per gallon” doesn’t quite do it…
Used to work just fine selling $50K+ Mercedes S Class turbodiesels. Back in the 80’s when $50K was much closer to buying a house than a car.
Lotsa folks ponied up good money for a 240D. In the 70’s.
Yes, fashions have changed. But the historical evidence is pretty well defined. It can be done, but ya gotta have the product.
porschespeed :
October 4th, 2009 at 6:30 pm
Used to work just fine selling $50K+ Mercedes S Class turbodiesels…
You’re right, I should have clarified a bit more – I think the market for econo-sports sedans is nonexistent. A diesel might actually be a decent engine option for a 5,000 pound luxury barge like a Mercedes S-Class, where top end power is less important than effortless speed off the line. But a 3-series BMW? That’s a sports sedan, pure and simple. It’s a car built for fast driving, and putting a less capable engine in it spoils the deal.
But, using your handle as an example, there are applications where diesel makes more sense. There would be nothing wrong with a torque-mosnter Cayenne, for example, but who would buy a diesel 911?
Hope that clarifies some…
But either way, I think the market for diesel luxury cars is simply limited given our current fuel situation.
Alright, seeing as I’m (apparently) being moderated in this thread, even after being slighted as an “internet diesel fanatic”, I’ll provide a report which supports my comments and disproves Pch101 claims.
The (private) 2008 report I have from Elf/PSA is an updated and expanded version crediting this original report format;
Diesel Dilemma: Diesel’s Role in the Race for Clean Cars
Take-aways from the report;
Pg11: Figure 7, ~20% improvement in economy on a GGE basis, ~15% reduction in greenhouse gases, ~10% improvement in economy expressed as a reduction of crude oil consumption.
Pg55: Table B-6, ~20 barrels of oil saved over baseline gasoline equivalent during the lifetime of a Taurus sized car. ~42 barrels using “clean diesel” or moderately advanced diesel tech available now (but not in the USA in 2004).
(Both of the above corrected to normalise engine power outputs).
While gasoline DI tech brings gasoline closer to diesel, it won’t approach advanced diesel tech until HCCI is widely implemented (when??).
Of course diesel saves greenhouse gases, even after refinement energy costs, but many here won’t care.
The report suggests advanced gasoline tech (including HCCI) is a more cost effective approach to oil saving and greenhouse gases reduction than advanced diesel. This is because of the energy and equipment penalties for controlling diesel emissions. Hybrid wins anyway, so fair enough.
To my original point, the refining ratio determines the marketable price for the various petroleum components, which then goes to cost effectiveness in oil consumption reduction. More diesel use might force the price up, it does save crude oil, but then diesel equipment is more expensive.
No one’s head needs to spin with specific gravity or fuel sold by weight.
No one’s head needs to spin with specific gravity or fuel sold by weight.
Of course. No point in allowing facts to intrude into the minds of diesel fans.
Take-aways from the report
You apparently didn’t even read your own link. From p. 2 of the document:
“Diesel’s oil savings and global warming benefits are often oversold. Low-sulfur diesel fuel is more oil- and carbon-intensive than reformulated gasoline; each gallon requires 25 percent more petroleum and results in 17 percent more emissions of heat-trapping gases. Thus, the fuel economy improvement afforded by diesel does not provide equivalent reductions in oil use and heat-trapping gases.”
Those are the implications of using a more dense fuel. The moral of the story: direct comparisons of diesel MPG and gas MPG are fallacious, and tend to get even more fallacious when the diesel devotees come out to play.
@ Pch101
Place that quote in the context of “Cost Effectiveness” as it is intended and then keep reading. Get back to us when you get past Pg11, specifically Figure 7.
Table 3 on Pg16 could be hard to explain too with MY2000 base tech vehicles compared giving the lifetime oil saving edge to diesel by 14 barrels.
Place that quote in the context of “Cost Effectiveness”
You could try putting it into the context of what I’ve been telling you throughout this thread, namely that diesel is a heavier fuel, which makes it impossible to reasonably make direct MPG comparisons with gasoline.
Your own link actually proves my point. Not that it isn’t difficult to prove, because I wasn’t stating an opinion but a fact.
Even when your own sources confirm what I’ve been telling you, you still don’t want to believe it. Think about the implications of that for a moment. They aren’t good.
@ Pch101
What is your explanation for Figure 7 on Page 11, and Table 3 on Page 16 (base column)?
“Comparing the fuel economy potential of similar gasoline and diesel technology packages listed in Table 3, it appears that diesel vehicles maintain their efficiency advantage and reach higher fuel economy levels than achievable with comparable gasoline vehicles.”
(After correcting for gge and power output).
The majority of the report is concerned with cost effectiveness, which you have not been arguing.
The best diesel engines can get peak thermal brake efficiencies of over 60%. The best gasoline engines peak in the 40s.
OK, who else thinks PCH and Pete need to get together and settle this over arm wrestling and beer?
:)
@ Pch101
Your opening gambit was;
“diesel is consuming a fuel that requires more oil to produce, creating an mpg difference which is largely illusory when accounting for the amount of oil actually being consumed”
Fuel does not exist in isolation, so the “chemistry of fuel consumption” is not complete until the fuel is actually used.
Diesel use would net 10% savings in crude oil consumption at worst, more given advancement in moderate diesel tech available now from VW/BMW. Ultimately HCCI is required to close the crude oil consumption gap to diesel in advanced technology diesel.
My back of the envelope 12% (from the BMW 335d) was out because of the energy input requirement to create low sulphur diesel.
My statement;
“MPG figures still roughly reflect the efficieny.”
Is wrong. The cited report suggests MPG figures should be adjusted down by ~20% to account for gge and power equivalence.
This is (one) of the points you make; MPG comparisons across different fuels should not be made. I apologise if I was arguing this point. As I’ve said before, and in my opinion for the work I do, grams of CO2 per kilometre shows the way, and perhaps THAT should be the singular measure of efficiency.
MPG works for the consumer because it is a multipler against price. That price is already set based on refining parameters/margin. Even so, the consumer can be assured that diesel use saves crude oil. (But go for the hybrids otherwise – which is a larger question on cost effectiveness in fuel efficiency).
People are interested in their spend (volume or weight per distance) however, so sale by volume continues. It’s also the only unit the refiner is interested in.
@ FreedMike
OK, who else thinks PCH and Pete need to get together and settle this over arm wrestling and beer?
I would be extremely interested to meet PCH and bring him/her a case of best Australian craft beer. Not sure on the arm wrestle stuff; he/she might be built like Hulk Hogan (I’m not).
I have to be in Chicago during January (not looking forward to being frozen through my bones I must say). Cold beer might not be the thing!
> Forty2 :
> October 3rd, 2009 at 2:24 pm
> The morons at VW USA decided to stick us with that
> ridiculous 2.5 iron 5-banger (along with the TDI)
> again. Base price of the gasser is almost $1200
> higher than ‘09!
> I’d be OK with that if instead of that heavy, lumpy, low-mpg five,
Just curious, have you actually driven the base I5 Golf?
Because I had very low expectation until I test drove one. I personally like it very much. The engine is surprisingly nice.
MPG works for the consumer because it is a multipler against price.
MPG is fine when comparing gas to gas, or diesel to diesel. It doesn’t make sense when comparing diesel to gas. Adjustments are required, and most oil burning diehards don’t bother making or understand the need for those adjustments.
Not sure on the arm wrestle stuff; he/she might be built like Hulk Hogan (I’m not).
Trust me, no need to fear broken limbs from me. But you won’t have room for the beer in your bag; you can’t face a Chicago winter without bringing a serious winter coat.
“Diesel would look about 15% worse if we used gCO2/km, since diesel has more carbon in a gallon than gasoline does, being more dense.”
The opposite is true. Please consult ComCar as an example.
You misunderstood me; I apologize for being unclear. I’m not denying that diesel still has an advantage. I’m saying that diesel looks about 15% worse using gCO2/km than it does using MPG or any volume based unit. It still has an overall advantage, yes, but the advantage (as far as greenhouse gas emissions go), is not quite as large as the MPG numbers would imply. This makes it inaccurate for diesel backers to tout an advantage– for greenhouse gas purposes– using MPG alone.
MPG works for the consumer because it is a multipler against price.
&
MPG is fine when comparing gas to gas, or diesel to diesel. It doesn’t make sense when comparing diesel to gas.
You’re both sort of wrong.
For the latter, it depends in which sense you mean to compare them. MPG makes a reasonable amount of sense if you’re a consumer who wants to know how far you can go on a gallon, and wants to compare pump costs. Consumers don’t, in general, really care about greenhouse gas emissions.
For the former, MPG is not a “multiplier against price.” The information that consumers have is $/gallon. You want to use a unit that has gallons in the denominator in order to multiply by the price per gallon. The problem is that you have to divide MPG and $/gallon to get either $/mile or miles/$. Multiplying is, as you note, easier for consumers to do in their head.
So for most consumers, gallons/100mi would be better for most purposes. You can multiply gallons/100mi by the posted $/gallon to get $/100miles, which is useful for most people. People consume miles (they really consume getting from point A to point B), they care about how many gallons it takes and how much it costs to go a certain distance. They generally don’t care about how far they can get on a certain amount, or about greenhouse emissions directly. One exception is when people are considering the question “How far can I get on a full tank?”
MPG makes a reasonable amount of sense if you’re a consumer who wants to know how far you can go on a gallon
Fine. But it doesn’t make sense to use it as an efficiency measure, which is the point that I’ve been making.
Diesel fuel takes up less space, resulting in higher MPG. That isn’t better or worse, just different. Comparing MPG between gas and diesel while claiming that one is more efficient than the other because of that MPG difference is illogical.
Gas and diesel motors are both highly inefficient, in that most of the energy in the fuel is lost as heat and doesn’t get converted into power output.
@ Pch101
… you can’t face a Chicago winter without bringing a serious winter coat.
My very first travel experience was to Chicago, and NOT having done my research, I did not bring anything close to “warm”. I was then clearly identified as an under prepared tourist/traveller at the nearest retail shop. I was completely GOUGED for thermals, a suitable-for-the-Arctic warm coat & boots! The sales staff sniggered openly as I handed over the cash.
Lucky I only carry a small amount of anti-USA bias from that event…. (Joking).
@ johnthacker
MPG is not a “multiplier against price.” ….. Multiplying is, as you note, easier for consumers to do in their head.
Yes, “multiplier” was the wrong word. I intended to mean that the consumer could work it out easily. I should have just said that.