From menno: “My Prius is now down to about 30 miles per gallon on E10 (real MPG, not on the computer – it’s showing 38.5 mpg). 130 miles on the trip meter and over 4 gallons used – you do the math. Just for the sake of comparison, before the loss of real gasoline, I was averaging 44 mpg (real calculations and on the car computer) in the winter, and about 50 in spring and fall, and 48 in the summer. This was with both the 2005 Prius and the 2008, over 48,000 miles on the 2005 and now having 21,000 miles on the 2008. Don’t know if the continuous E10 has made the difference between the computer MPG and calculated MPG, but there is essentially no point in having a Prius anymore. The Prius sucks ethanol tainted fuel like a drunk at a free bar. My wife’s (way) less expensive to buy, more comfortable, zoomier, roomier and nicer Sonata averages MPG in the low-mid 20’s in the winter, 26-27 in spring, summer and fall, and did 32.2 mpg on a 5000 mile trip on expressways and in mountains. As soon as gas prices hit $3.00 a gallon I’m putting the Prius up for sale. Recently, the last gas stations in the area stopped selling 100% gasoline (it was BP). The resulting MPG loss was immediate.” And he’s not the only one who’s turning his back on E10…
“The newly-reopened Rhoades’ Service Center on Western Avenue in Albany started advertising 100% ethanol-free gasoline on Tuesday,” Fox23 reports. “The gas station is one of a handful in the Capital Region that is offering fuel that doesn’t contain the environmentally-friendly additive. Station staffer Bob Haines tells us, ‘We know a lot of people involved with motor sports and using small engines for their businesses (landscapers, snow plowers, and whatnot) and that’s why we went ethanol-free.'”
But what if car drivers like menno start showing interest in ethanol-free fuel? Could this become a trend? If so, it would be a nail gun rat-a-tat-tatting on E85’s grave. On second thought nah. One should never underestimate the power of political correctness and special interest lobbying. If it gets big enough, the state’s will simply ban it for cars. Done.
I had an idea for a website and/or an iPhone widget for people to find gas stations that sell 100% pure gasoline. Maybe someone on here can run with the idea.
Ethanol is playing havoc with the two carburetors on my boat, and these are not small engines. I pulled them off last weekend and they were all gummed up ( the boat ran fine in October).
I haven’t had a problem with the carburetor in my 1979 Lincoln yet but the mileage has suffered. I was getting over 11 MPG on pure gasoline, now it struggles to get 10MPG. Thats like a 10 percent drop.
I was getting 31.5 MPG with pure gasoline in my Corolla and it’s getting 27.5MPG on E10. (menno: It seems like Corolla costs half as much as a Prius for only a 2.5MPG fewer miles on E10, at least.)
My 2003 Chevy Silverado got about 17.5MPG, now its getting exactly 15MPG.
It is almost as if the ten percent ethanol has absolutely no energy content because I am getting about 10% fewer miles to the gallon with it.
The stuff can not go away fast enough, in my opinion.
I can’t remember the last time I saw pure gasoline. Has anyone in Chicago seen it in the last few years? My STi is rated 18/24, and I drive/shift pretty conservatively and get about 17/21 or so. I have only ONCE seen 24mpg and that was 100% highway trip at 60mph.
Who do we have to contact to get stations to sell pure gasoline again in the Chicago area?
I too have seen at least a 10% drop in efficiency when I’ve got E10 and avoid it wherever possible. I hate ethanol and all the absurdity behind it.
Unfortunately for the farmers, they’re not really making any money on the higher price of corn as they now have to pay more for fertilizer and seeds and more.
On another note – the computer showed a 28% high readout? And only when the MPG was low? That’s a little… sneaky.
The government spends billions on promoting and researching Global Warming
Then the governments spends billions on producing and forcing the puiblic to use ethanol
Ethanol causes more environmental problems than it solves and is a crappy fuel compared to gasoline.
Voters vote for more of the same.
Economy collapses.
Local gasoline retailers are legally required to contaminate gasoline with 10-percent ethanol. To my knowledge only Shell premium, marketed as V-Power, is ethanol-free. The mileage boost helps offset premium’s additional cost. It is also designated Top Tier, supposedly a good thing.
Ethanol is a crock of sh1t. Growing corn for fuel isn’t feasible no matter what you do. And instead of increasing fuel economy, it decreases it. Even though they can apparently mix ethanol into diesel, I’m glad not much has happened with it yet. I’d be ever so annoyed if my TDI went from an average of 50 MPG to 30. At least when winter comes I expect to get lower mileage numbers with winter diesel. For the people buying gasanol, it’s going to be year round.
In my experience, fuel mileage gauges are tied directly to the throttle position sensor – regardless of if it’s mechanically connected to the pedal or not. This also uses information from the engine speed. So in reality, it’s “estimating” what the fuel economy is based on these few parameters.
In reality, fuel flow at the injector varies continuously based on load and demands. Combine that with the PCM trickery needed to modulate fuel flow for the idle start/stop feature on the Prius, and I can see where the reality of fuel consumption can diverge drastically from the estimate the computer is generating from a few cherry-picked, calculation-massaged information sources.
With all due respect to menno (and I really mean that), I don’t give a lot of credence to his assertions that E10 drives down mpg that much. A 130-mile trip isn’t enough data, and yes, I know he’s made extensive claims to the same effect about his other cars over the decades. One other poster made the point earlier that ethanol contains SOME energy, just not as much as pure gasoline. Therefore, a 10% ethanol content should correspond to LESS THAN a 10% drop in gas mileage.
I’d say a precise scientific test is in order. Take a car (let’s use the Prius for starters), drive it on a test track in a prescribed manner starting with a full tank of E10. Refill tank without ethanol in the gas and repeat. Drive at least enough to use up a full tank. Then compare.
I know with my 3-vehicle “fleet,” on which I keep complete gas records, that I have seen no noticeable trend over the past 4-5 years toward lower mileage since gas containing the vague “up to 10 percent ethanol” has been introduced.
How I drive, where I drive, ambient temperature, a/c use, and filling error (not completely topping off) all seem to mask any mileage differences due to ethanol content. (And like I said, you often don’t even know how much ethanol, if any, is in a given tank.)
Still, I think ethanol is a boondoggle and the ONLY reason it should be used is as an oxygenate for emissions purposes in the mainly metro areas that require such measures.
About trip computers, the only one I’m familiar with (in one of my cars) is ALWAYS optimistic, sometimes absurdly so. I never base my records on what it says. But my limited time in driving Priora seems to indicate these have more accurate computers.
I’m having trouble wrapping my head around this problem. I desire to lower my pollution/carbon footprint, yet I’m sold a fuel that is “oxygenated”, yet requires me to fill up more often to go the same distance (cue the sound of a cuckoo clock).
I can say that after 3000 miles, the MPG on my Hyundai Elantra has been dropping steadily (due to the short commute that I have and the onset of winter and longer “warm-ups”), but it’s been up and down as far as matching the MPG readout. I’ve had readings of 1 to 2.5MPG lower than my calculated mileage, and the only thing I can think of is the varying amounts of ethanol being mixed into the gasoline (Giant Eagle grocery store gas with discounts for gas purchases). Their pumps (recently) started displaying the PA required “Contains Up To 10% Ethanol” stickers, but I’m sure that that crap was in there before.
As an experiment, I stopped into a Citgo (yes, Chavez) last night and filled 11.6 gal of 14 gallons – Their pumps did not have the label about ethanol (so maybe I’m getting the real thing). I’ll attempt to drive the same and see what happens…
I not sure why an MPG meter “calibrated” on 100% gasoline could read optimistically when fed a 10% ethanol mixture – the density of the fuel may be different enough to “fool” the computer that it’s delvering a full charge to the injector, yet when that fuel explodes, it’s generating less power, so you need more throttle?
I’m too dumb to figure this out on a Friday…
npbheights – I’ve read several reports about the problem with E10 in boats and personally know someone that has been effected by it pretty badly. The best solution (other then finding 100% gasoline) is PRI-G:
http://www.priproducts.com/prigproduct.htm
I’ve been using it for several years in my boat – it fires right up every time right away and runs great. A buddy of mine turned me onto the stuff awhile back, so I figured I’d pass along the info and recommendation.
Interesting comment about the V-Power. Last month I tested one of my non-hybrid car’s on a long (450+ miles each way) trip. On the trip out, I the computer registered about 38 mpg averaging in the low 60’s for speed. On the trip back I averaged 33mpg at 73 mph and more rest area stops than the trip out. I expected a larger difference in MPG, but come to think about I used V-Power Premium for the trip back and the trip out was with Hess Premium. Maybe that explains it.
If I remember correctly the Prius has to run it’s ICE more in the winter to provide heat. That could be a factor as well. My Prius is sucking down more gas this winter, but still stays in the upper 40’s in lots of stop and go traffic. We feed it mostly Mobile regular.
I live just down the road and was discussing it with my coworker this morning. I cant wait to start using ethanol free gasoline again.
Same thing in my Volvo turbo. Highway mileage went from 25m/g to 22. I try to avoid ethanol as it pulls moisture out of the air and into the fuel system. In a car not designed to accept this sort of abuse the fuel system can corrode and gunk up. Over time you get an additional loss of performance and repair bills. I’d pay $0.20 more to avoid E10 and figure I came out ahead right now.
I agree that as a country we need to move away from gasoline dependent locomotion. It is a national security and balance of trade nightmare. The only thing I think can replace it will be electricity produced by coal and nuclear plants once we can work out a suitable storage device.
With luck, that is nearly done. Years ago an EE told me that physics allowed a many order of magnitude improvement in electrical storage over current battery technology. It was just a matter of time before we figured it out.
How the hell does a Prius get only 30mpg? That’s about what my Civic gets after hard driving, on E10. And I doubt anyone who owns a Prius, or any new Toyota, takes it to attack the switchbacks.
Back in the old days, VWs had mpg computers that used engine vacuum and vehicle speed to estimate mpg. I believe my ’98 still does it this way. It’s reasonably accurate, +/- 1 mpg, but obviously could only work for one kind of fuel. To calculate mpg for flex fuel vehicles you’d have to monitor fuel pressure and count injector pulses.
Some areas like southeastern Wisconsin mandate 5% ethanol in fuel for smog reasons. Wouldn’t the V-Power contain ethanol in those markets?
I know TTAC is not a science blog, but I think it’s a little irresponsible to publish these kind of claims without any kind of controlled testing. I don’t doubt that menno’s mpg have gone down, but there should be some kind of attempt to explain it instead of simply blaming E10.
E10 is 10% ethanol. Ethanol has about 1/3 less energy than gasoline. So a car running E10 could reasonably expect to see about a 3% drop in fuel economy vs. regular fuel. A hybrid should see even less impact since it doesn’t always run off the gas engine. This would not explain in any way the drastic reductions in fuel economy reported here.
Now, I’m not saying this means E10 can’t be at fault, but to jump to the conclusion that it is is very premature. A controlled test should be performed using gas and E10 from various sources, with the car driven in the same test loop each time. If significant differences are still found, it still begs the question why, as the answer is certainly more complex than just having E10 for the fuel.
Thanks for the kind thoughts, 210Delray, but according to what I see, you’re 10-1 outnumbered (9 others and myself) in comments directly stating that efficiency drops on E10.
As for my snowblower, it now runs like cr@p, and I have to keep the choke on (very slightly) as otherwise, it lean-misfires constantly. Obviously, due to the ethanol which is an oxygenate. Probably also due to the fact that small engines hate ethanol. And the fewer BTU’s of ethanol (about 85k per gallon vs. 117k per gallon for pure gasoline). The Prius is not malfunctioning, because the snow blower started playing silly buggers at exactly the same time that the MPG plummeted in the Prius – not coincidentally, this was at the same time that the last station in the area started pumping E10. Also, the check engine light has not come on, in the Prius, nor did it come on in previous “tests” of E10 (where I saw MPG plummet).
You could say that quite literally, ethanol sucks.
If we have to have ethanol, put it in Flex Fuel vehicles as E85.
E10 is a total waste. Even if you lose 10% MPG on E10, it is costing us extra oil imports, as it costs money (and oil/natural gas) to plant, reap and convert corn to ethanol then it must be trucked for mixing with gasoline since it can’t be put into an oil pipeline.
Putting ethanol in gasoline engines is simply mis-fuelling them.
@JMII
Thank You for the tip, I will try it out.
Redrum, I was as surprised (and po’d) as anyone when I found that suddenly, my “calculated” MPG (which went from 43 to 45 mpg in the winter to 37 to 39 immediately at the loss of the last non-E10 station in town) was in fact really now 20% -25% out from reality. Overall, previously, the computer generated MPG and real-world MPG have been so close that I have skipped calculating out the MPG except as a periodic double-check.
But there is absolutely NO other reason for this MPG loss. The car is running fine.
Redrum, I’ve looked and seen plenty of people who are also saying that Prius MPG goes south on E10. I have to wonder if the Atkinson cycle engine simply does not cope well with E10. If this is so, then the Toyota and Ford hybrids are going to be hit harder than the Honda hybrids, which use the “normal” Otto cycle engine.
I’m curious. Why is reporting the truth as I plainly see it “irresponsible”? I’ve been measuring gas mileage since 1973, and have tested virtually every car I’ve owned (over two dozen) since 1979 on E10 vs. gasoline and never see anything but an efficiency drop.
Is it “irresponsible” or “judgemental” to say “raindrops make you wet”?
I can also – briefly – explain my theory as to why cars don’t do well on E10. Ethanol is an oxygenate. Most cars since 1984 have oxygen sensors on the exhaust which control fuel injection in order to keep a stochiometric (sp?) or 14.7 to 1 air-fuel ratio, in order to make the 3-way catalytic convertors reduce NOx, CO and HC. Otherwise, the cats can’t do NOx. With E10, obviously the amount of LIQUID FUEL is increased minutely due to the ethanol (remember, it is an oxygenate – contains a lot of oxygen compared to gasoline). A richer LIQUID mixture of E10 then dumps yet more oxygen into the system, and it then must continue that cycle until it stabilizes (at a significantly richer true LIQUID FUEL to air mixture). PLUS ethanol has much less energy than gasoline, and engines running rich on a LIQUID FUEL basis make less power than one running properly lean. Less power means one purshes the pedal harder – we are creatures of habit and want the power we expect of a given vehicle. Obviously, it’s a self-perpetuating cycle of more fuel being burned for fewer results.
That’s my theory, anyway.
@menno: As for my snowblower, it now runs like cr@p, and I have to keep the choke on (very slightly) as otherwise, it lean-misfires constantly.
Funny you mention that. I finished the can of gas left over from the summer in my snowblower and just switched to the ethanol stuff. It was running fine before, now I have the exact same results.
I’ve been skimming the Shell site for V-Power info, and so far there is no mention that it’s ethanol free. Just detergent additives.
Here’s some info on “Top Tier” fuels.
http://www.toptiergas.com/deposit_control.html
For those of us who have suffered with ‘oxygenated’ fuels for many years, this is not new.
Beyond the gum/clog/varnish aspects, the performance and mileage suffer.
If you use a fuel stabilizer anytime you are leaving your toy or weed whacker sitting for awhile, you’ll be fine.
As to MPG gauges, I guess there might be some of them that are still vacuum driven, but in most EFI applications there’s easy instant data available from the ECU.
They generally take the injector pulse-width, road speed, and smooth it out a bit. Pretty straightforward and generally damn accurate.
Gas mileage on my ’99 Accord dropped not quite 10% after they started using E10 i the Boston area. I’d go out of my way to a station that had pure gasoline
I don’t know how things are in the US, but here in Canada, Shell has three grades of gas. Bronze is basic, and the pump states it can have as much as 10% ethanol. Silver is mid-grade and can be as much as 5% ethanol. V-Power is top-grade and is stated as having no ethanol in it at all. is higher as you go up in grade too, obviously.
In this area Shell V-Power gasoline pumps display a prominent sign stating, “Contains no Ethanol”. I suppose they sell sufficient regular and mid-grade gasoline containing ethanol to achieve the legally mandated 10-percent retail sale ethanol ratio.
@menno: My 82 Turbo has a oxygen sensor so it goes along with your theory. I had the same idea. Anyone else think menno has explained the observation?
My suspicion — and I’m not an engineer, so I’m guessing — is that hybrids like the Prius suffer greater mileage losses on alcohol-blend fuels than conventional engines.
Ethanol has only about 70% of the thermal energy of gasoline. In an electronically controlled engine, the engine computer will ensure that you have comparable power output (perhaps a little more, because ethanol has a much higher octane rating than even premium unleaded), but fuel economy drops commensurately, because you get less energy out of each gallon burned.
The Prius has an Atkinson-cycle engine, not an Otto-cycle engine. With the Atkinson cycle, the intake valves stay open well into the compression stroke, allowing some of the intake air to be forced out into the intake runner. The mixture that’s burned is therefore less dense than an Otto-cycle engine with the same compression ratio, but the expansion ratio is the same — the result is greater fuel economy at the expense of power output.
Since the Prius’s mixture is less dense, if you run a blend of ethanol, the alcohol’s lower thermal energy is that much more significant. Again, the engine computer compensates by burning more fuel, but the result is an even sharper drop in fuel economy than in an Otto-cycle engine running the same fuel.
Menno: When TTAC posts this under the heading “E85 Boondoggle of the Day” with no disclaimer, I consider that irresponsible. I didn’t say I thought you were irresponsible, obviously you are reporting your observations. But if TTAC wants to be taken seriously it should take a little more responsibility than just passing through whatever supports their viewpoint.
I have no idea if your theory is valid, but I have found no documentation to support it. Every article I’ve read about E10 verifies the basic math of the situation — it reduces mpg by about 3%.
Like I said, I don’t doubt you’re seeing a big hit in fuel economy. But without valid testing under controlled conditions, it doesn’t prove anything about E10.
If my car’s trip computer was erroneously reporting 8 or more MPG higher than what I hand calculated, it would be in the shop with a very angry customer sitting on the other side of the counter demanding a repair. My 2007 Malibu 3500 V6 usually averages 26-27 MPG in normal driving and with the 10% Ethanol it only goes down less than one MPG if that so it really doesn’t show. The huge difference is mileage on the Prius would make me want to unload it quickly.
Menno:
Redrum basically said what I was going to say: it’s TTAC that’s irresponsible for passing along anecdotes instead of data from controlled tests. (Obviously, my experience by definition is anecdotal as well.)
I’d like to see such a controlled test, as I can’t even say in my area (central VA) how much ethanol I’m actually putting in the tank. Most pumps here are labeled “contains up to 10% ethanol” or “may contain ethanol,” so I really don’t know. Plus I still think (but can’t say with absolute certainty) that the other factors I mentioned (how and where you drive, ambient temperature, a/c use, different gas pump shut-offs) would overwhelm any mpg differences attributable to E10. This would certainly be the case if E10 reduced mpg by only 3% — then you’re into decimal dust in the absence of controlled testing.
I went from about 360 miles/tank (~18 gallons)
to about 270 miles/tank now on the E10 in my Rodeo driving to work. That is a 25% decrease. Nothing to scoff at. E10 is bad for mileage.
Redrum basically said what I was going to say: it’s TTAC that’s irresponsible for passing along anecdotes instead of data from controlled tests. – 210delray
Would those be like the EPA controlled tests that overstate fuel mileage 25-percent to 40-percent?
menno,
I wonder if your snowblower, (and other carbureted engines,) need the extra choke due to stoichiometric differences. Gasoline is 14.7:1, but E10 is only around 14.1:1. That’s not a big difference, but might explain the slight leanness you see. Just a thought.
Sure there’s a point to owning a Prius with E10 – everyone else’s mileage will go down too, and 30 will seem like a lot! My Miata gets close to 20mpg on E10 (my norm is 25mpg, which is sad for a lightweight 142hp car but typical Mazda).
But why would a Prius be affected by E10 more than other cars? The engine isn’t that much different.
I have no idea if your theory is valid, but I have found no documentation to support it. Every article I’ve read about E10 verifies the basic math of the situation — it reduces mpg by about 3%.
But that’s the thing about the math; it’s too basic. It doesn’t necessarily account for any differences in combustion efficiency that result from using a fuel for which the engine wasn’t optimized.
Would those be like the EPA controlled tests that overstate fuel mileage 25-percent to 40-percent?
Overstate? They actually intentionally understate mileage using a correction factor to account for poor driving habits. My average mileage, including both city and highway driving, is typically higher than the EPA highway rating.
It really is odd that I’m forced to use E10 in my car even though I’ve never seen an actual study about the effect of E10 on fuel economy.
Gardiner Westbound:
The 2008 and later EPA numbers certainly don’t overstate gas mileage. I mean, unless you’re always on the “go” pedal (or snarled in really bad traffic like in L.A.), you should have no trouble meeting or exceeding the mpg values.
@ rpn453: The Prius’s engine is different from other cars — Atkinson cycle vs. Otto cycle (see above). I suspect that makes a difference.
jgh & roadracer,
Re: MPG displays
The ECM programs for fuel injected engines that I have worked on, based injector pulse width on many factors, including throttle position, gear, engine RPM, manifold air pressure, coolant temperature, battery voltage, O2 sensors, fuel pressure, and fuel temperature. And the flow rate of the injectors was well-characterized. Using this info, the ECM kept a running sum of the fuel used. This info was passed to the body computer, which calculated and displayed the mileage. Even with all that, every one I’ve tested seems to display an optimistic MPG on the display. Go figure.
As to the error created by adding ethanol, the only thing that comes to mind right off is injector flow rate differences, perhaps based on (the relatively minor) viscosity differences. But that’s just a guess. Any other change (O2, thermal energy, etc,) would still be handled by knowing the injector pulse widths.
Isn’t E10 the same thing as “gasohol?” If so, it has been for sale in Illinois since Jimmy Carter was president.
I believe that Illinois mandates the use of E10 statewide now — not surprisingly, as ADM is headquartered here.
I’m pretty sure we have been using ethanol in Chicago for a long time. As I recall, one of the goals of the Clean Air Act of 1990 was to reduce air pollution in cities, and adding ethanol to gas was one of the methods that was used. I’m not sure if it was E10 or not — it may very well have been less than 10% ethanol. But the “May Contain Ethanol” stickers have been on gas pumps here for as long I can remember.
My cars have always gotten pretty much what the EPA said they would as far as mileage is concerned. But that is purely anecdotal, obviously.
But that’s the thing about the math; it’s too basic. It doesn’t necessarily account for any differences in combustion efficiency that result from using a fuel for which the engine wasn’t optimized.
Modern cars built by Toyota and other automakers were designed specifically to run on a blend of 8-10% ethanol. http://www.toptiergas.com
I’m sorry, but there are numerous flaws here. For one, those fuel economy gauges are inaccurate and can’t be used for precise measurements. For another, each driving cycle is unique and a lot of factors can cause a loss in fuel economy.
Redrum is correct. E10 should lose about 3%, not 10%. Without testing it in a lab that controls for all variables and ensures accurate measurements, there is no way to believe this post.
We can debate ethanol as a policy, but a lot of the commentary about it comes completely out of left field and I just can’t take it seriously. To claim a 10% loss in fuel economy from E10 is completely outlandish and makes no scientific sense at all. This would be akin to saying that alcohol has no energy content, which is completely false.
The Prius’s engine is different from other cars — Atkinson cycle vs. Otto cycle (see above). I suspect that makes a difference.
I said it’s different, but it’s not that different. Certainly not different enough to decrease mileage by 30% while regular engines see losses in the single digits! While you’re here . . .
In an electronically controlled engine, the engine computer will ensure that you have comparable power output (perhaps a little more, because ethanol has a much higher octane rating than even premium unleaded), but fuel economy drops commensurately, because you get less energy out of each gallon burned.
I don’t believe an engine can make more or even the same amount of power from 87 octane E10 as it can from 87 octane regular gas. Do you have anything to back up that claim?
In an electronically controlled engine, the engine computer will ensure that you have comparable power output (perhaps a little more, because ethanol has a much higher octane rating than even premium unleaded), but fuel economy drops commensurately, because you get less energy out of each gallon burned.
Octane rating is just a measure of resistance to pre-detonation at certain temps and pressures. It doesn’t measure the energy content of the fuel at all. High-octane works in high-compression engines better as a result, or engines that run hard and have a hot exhaust valve. But the engine’s compression ratio is a fixed mechanical property, just a volumetric ratio of the cylinder between BDC and TDC. In an engine that burns just fine at 89 octane, putting 99 octane in it is pretty pointless. Ditto for ethanol.
The Prius’s engine is different from other cars — Atkinson cycle vs. Otto cycle (see above). I suspect that makes a difference.
That would be a factor I think on the Prius. The ideal Atkinson setup expands the charge on the power-stroke to ambient pressure. Change the chemistry in the propellant and you change both the mass and the heat product of the charge, and that will screw with that ambient pressure ideal.
I don’t know enough about ethanol as a fuel, but with the lower heat and lower molecular weight of alcohol, I would suspect in an Atkinson designed for gasoline that doesn’t compensate for the difference with ethanol you would get a lower-than-ambient value in the cylinder at BDC before the exhaust valve opens. Sadly, with both valves closed in that situation, that would force the engine to spend some energy essentially working like a vacuum pump on the bottom of its power-stroke.
Well, sodium is an explosive, alakaline metal, and Chlorine is a poisonous gas. Together, they form a much milder corrosive compound, salt.
Ethanol attracts water, if the ethanol is mixed with gasoline at the terminal (which I believe it is), then the handling and storage of said ethanol will determine its water content.
Gasoline + ethanol + water carried by ethanol.
I don’t believe my ECU is programmed to get the most efficiency out of a variable blend like that.
(I like the “conspiracy theory” aspect of this discussion. I think “THE MAN” will stick it to us any chance he gets.) ;-)
Modern cars built by Toyota and other automakers were designed specifically to run on a blend of 8-10% ethanol.
You could be right. Do you have a source? I would have thought that they designed the engine for 100% gasoline, since that is how the EPA testing is done, and then ensured that it could simply accomodate the presence of 10% ethanol. They certainly didn’t design E85 capable engines for E85; the engine has the same compression ratio whether it’s running E85 or gasoline!
This:
http://www.ethanol.org/pdf/contentmgmt/ACE_Optimal_Ethanol_Blend_Level_Study_final_12507.pdf
was the most scientific study I could find (in 10 min of searching) regarding fuel economy and emissions for ethanol fuels vs normal gasoline. It was sponsored by the ethanol industry, but they use a chassis dynamometer and standard fuel blends which are repeatable and leave little room for undue influence.
Whats interesting is that the results differed by car type significantly, and the flex fuel Impala tested actually got better mileage on ethanol blends than with regular gasoline. Here’s the interesting quote from the executive summary:
“HWFET testing on ethanol blend levels of E20 in the flex-fuel Chevrolet Impala, E30 in the non-flex-fuel Ford Fusion and Toyota Camry, and E40 in the non-flex-fuel Chevrolet Impala resulted in measured miles-per-gallon fuel economy greater than predicted based on per-gallon fuel Btu content. It is notable that the non-flex-fuel vehicles obtained greater fuel economy at higher blends of ethanol than the unleaded gasoline. In the case of the flex-fuel Chevrolet Impala, the highway fuel economy was greater than calculated for all tested blends, with an especially high peak at E20. While only three non-flex-fuel vehicles were tested in this study, there is a strong indication that non-flex-fuel vehicles operated on optimal ethanol blend levels, which are higher than the standard E10 blend, can obtain better fuel mileage than on gasoline.”
what does this all mean? Like most subjects worth debating there’s no clear answer and its all shades of gray. But we definatly shouldn’t make broad generalizations like “ZOMG all ethanol bad!!!111”.
Do you have a source?
I linked it in the same post.
Read about what “Top Tier” fuel is, and you will see that it requires that the fuel be E8-E10.
Toyota is among those companies that formulated the fuel standard. They are encouraging you to use E10 fuel that has this designation.
@ rpn453: E10 has a slightly higher octane rating than straight regular-grade gasoline. The research octane number for ethanol is like 116 or 117, whereas regular unleaded is usually 91 RON (note: RON is somewhat higher than the “pump octane” average posted on U.S. gas pumps). Octane numbers for blended fuels don’t increase on a straight average (i.e., a 50/50 mix of 90 and 100 octane fuels is less than 95 octane), but there is a slight increase.
Most modern engines have knock sensors that adjust the timing to avoid detonation. Depending on the way the ECU is set up, some cars will advance the timing (and, for some turbo engines, the boost pressure) as far as the fuel octane will allow, which will give you more power on high-octane fuel — like, say, the 100-octane unleaded racing fuel you can buy at a 76 station near here — than on regular. (Some will not; if the ECU doesn’t allow the timing to advance with higher-octane fuel, it will have no effect.) In that case, a gasoline-alcohol blend may allow greater spark advance than straight gasoline. With an E10 blend of regular unleaded, though, even if there were an increase, I doubt it would be noticeable without a dyno test.
Edit: GeeDashOff has read my mind. Now where did I put my tinfoil…?
OK time for some science…
http://www.ethanol.org/pdf/contentmgmt/ACEFuelEconomyStudy_001.pdf
Now, I do somewhat question the results, because looking at the methodology, it would appear they have not effectively captured for a wide enough array of vehicles. That having been said, the rest of the methodology appears sound from a quick re-read (forgot all about this one).
It’s a quick read for those who really care.
@ CarnotCycle: I know the ECU does not actually measure energy content of the fuel. I was being simplistic. But the engine computer will alter the air-fuel mixture to compensate for alcohol fuel, in a way that generally gives the same power, but poorer fuel economy, which was my point.
Octane requirements are only partly based on static compression ratio; they also depend heavily on spark timing, which on modern engines self-adjusts (via the knock sensors) to minimize detonation. If you advance the spark timing a bunch, the octane rating will go up a bunch, without altering the compression ratio.
There may be more at play than just ethanol. For example, ethanol lowers the Reid vapor pressure, which means that some components distilled from oil can’t be used (pentane and butane?) because the resulting mix of fuel would just evaporate out of your tank on a hot day. This is especially the case with California’s tougher fuel emissions standards. Here in California we have “California Reformulated Gasoline version II” in some areas and “Federal Reformulated Gasoline” elsewhere. I, unfortunately, have the former around me and notice that my car loses power and efficiency with the stuff.
I have a notebook where I record fuel use and mileage and have noticed the difference. The best mileage I have *ever* seen on California RFG II is 24 MPG (that includes several highway-only tanks over the course of 6 years’ car ownership). When I go to Yosemite, I start from home with just enough gas to make it to the central valley, where I get Federal RFG gas. Then from the central valley I drive to Yosemite and back to the central valley (i.e.: no elevation gain or loss) and have always managed 27 or 28 MPG–often with the A/C on and with 2 to 4 people and camping gear.
The gas station is one of a handful in the Capital Region that is offering fuel that doesn’t contain the environmentally-friendly additive
No green-leaning person I know considers ethanol to be environmentally-friendly. Not. A. Single. One.
This is a greenwash, designed to funnel funds to Big Farm and allow certain automakers a CAFE freebie. It’s stuff like this that gives environmentalism a bad name.
I linked it in the same post.
I see. You wanted us to go digging in the “Deposit Control” section!
I really just want to see some real numbers for a large sample of cars. It would be nice to look at EPA test results for both E10 and 100% gasoline to see how it affects your specific car. I can buy 100% gas (premium) here for 5% to 10% more than the “May Contain Up to 10% Ethanol” pumps. It’s almost certainly not worth it, especially since the possible E10 might not even contain any ethanol, depending on the blend. But it would be nice to know for sure.
Interesting study, GeeDashOff. That’s the sort of thing we need to see more of. I was surprised to see some ethanol blends perform better than pure gasoline in some engines during that test.
87 octane E10 vs. 87 octane gasoline. Ethanol has roughly 115 octane rating right? What is gasoline’s octane number? How about it’s exact energy content? It doesn’t have either because gasoline is made up of other aliphatic hydrocarbons with added octane boosters. It’s energy content can vary up to 4%. So essentially gas companies can mix 90% 84 octane gasoline with 10% ethanol to produce 87 octane E10. Essentially gas companies mix 84 octane crap gas (possibly lower energy content – who knows?) with the ethanol and everybody blames ethanol. Genius! With market opinion against ethanol it will never gain market share. Two birds with one stone.
I’m pretty sure I can’t buy any non E10 gas here in NY.
Personally I think “Top Tier” is anti ExxonMobil marketing propaganda. I guess if people go for it then more power to Shell, Texaco, Chevron, Philips and the others.
Please keep in mind that many of us are required to use E10.
Non-optional. EPA mandated. This is (right, wrong, or indifferent) a pollution mitigation step.
Ethanol may suck, but it is nothing compared to the environmental nightmare that was MTBE.
BTW – If you think E10 is hard on your car, just be thnakful that your weren’t in CA when MTBE was the oxygenate of (non) choice.
Lots of really interesting and insightful comments (some agreeing with me and others not – but that is what makes an intersting and though provoking “conversation”, no?)
OK, so after about 7 or 8 weeks of running E10 (aka gasohol), the Prius is obviously purged of 100% gas. So, in the interest of science and for further discussion sake, I just went and filled up Prius. It’s 23 degrees F. It had 154 miles on the trip meter, trip computer said 37.9 mgp, the filler (running at the lowest flow /first click at the station near home) clicked off at 3.8 (US) gallons, so in line with my usual practice, I pushed another gallon in. I’ve never had gas on my shoes yet.
Computer readout 37.9 mpg
154 miles / 4.8 gallons = 32.8333 MPG.
So that’s about 10% better than I had anticipated and estimated (which is good) but still the car is using about 34% MORE FUEL compared to my historical winter norm of 44 mpg on pure gasoline.
(Obviously bad).
The running tally MPG meter is seemingly running 15% out (bad) when, over nearly 70,000 miles in 2 Prius cars, it’s usually nearasdamnit right.
Before I bugged out to the station, I made a mental note. 33 mpg real or better, and I’ll reconsider keeping “Pope Prius” – so for now, until and if I don’t see a drastic change (obviously taking into account my normal winter 44 mpg, spring/fall 50 mpg and summer 48 mpg bogey points), down the road it goes once gas hits $3 a gallon and people start to excrement their shorts over the price of gas yet again.
(My pal named the car “Pope Prius” as it is white, whereas the 2005 car was silver and remained nameless).
I’m not sure which is sillier: Corn-fed gasoline that costs more energy to produce than it generates, or goofy golf carts that use $3,000 worth of disposable batteries to save $300 in fuel.
The fact that these two “technologies” should find themselves fighting with each other is something that only John Cleese could truly appreciate.
I don’t know about the drop in mileage but this
The running tally MPG meter is seemingly running 15% out
explains the difference in you computer reading and you actual measured mpg. The running tally is an average of the gas mileage since the last time it was reset. So if you ran 3 tanks of gas and average 40 mpg then your 4th tank was 30 then the overall average would be 40+40+40+30=150/4=37.5 is what the computer would read even though you last tank was 30mpg. If you reset the computer each time you fill up the computer mpg and your actual calculated mpg would be very close.
While the gasoline-vs-E10 debate is very good and I don’t want to distract from it, I’m very concerned about the findings that the car MPG reading is so far off from reality.
I suspected for years that I couldn’t trust the automatic computers because there would be every incentive for the manufacturer to make them appear better than normal. But then I learned that the external computers, like the ScanGaugeII, are supposed to be extremely accurate about fuel consumption, so the built-in computers obviously would be at least as good.
If the type of fuel you use can throw off a ScanGauge so easily, I probably should cross it off of my birthday list.
Haven’t found a gas station in Illinois that has ethanol free gas but usually if you are in an area which deals with a lot of boats they will usually have one pump with 100% gas – you might have to ask 1st
Incidentally all the VPower shell pumps in the chicago area (that Ive been to) are 10% ethanol
nonce-
The ScanGauge is a damn accurate tool.
I’m really not sure what could be causing these apparent inaccuracies, as far as I can tell, the Prius calculates instant mileage the way most modern cars do – by taking injector pulse-width (how much fuel is delivered) and a reading from the ABS sensors (how fast are you moving).
That’s all the data one needs. MAP, IAT, TPS, CLT, etc., all irrelevant. All that matters is how much fuel is squirted into the engine and how far did you travel.
I’ll check the densities again. But that really can’t account for the instants being that far off.
My driving cycles seem pretty consistent to me. I also tend to buy fuel from the same service station every time. Yet even I get swings in fuel consumption of 20% or so from tank to tank, even though I make some effort to reduce the variables.
I also find that the onboard computer is inaccurate. It is almost always optimistic, and the results are often 5-10% higher than what I calculate when comparing the change in odometer reading to the amount of fuel needed to fill the tank between fillups.
The problem here is sample bias. You may think that your driving is consistent, and the mileage should therefore be the same, but it isn’t. So the mileage may vary, even when all factors seem to be equal, because they aren’t equal.
Toyota wants you to use E10 ethanol, because of its detergent value. The company that made your car wants you to use it.
There is no logical way to blame the fuel for 100% of the changes in fuel economy. Obviously, if you have a phobia about ethanol and are looking for excuses to blame the fuel, then the facts aren’t going to matter, regardless.
Incidentally all the VPower shell pumps in the chicago area (that Ive been to) are 10% ethanol
That’s because Shell sells the “Top Tier” fuel that several automakers want you to use, and Top Tier fuel is supposed to have ethanol in it.
@PabloKoh: I came up with up to 3.3% loss with use of 10% ethanol and up to 5.3% additional loss to the, enabled by ethanol’s high octane, mixing with trash gasoline. Here we are already at 8.6% less not even accounting for throwing off of an O2 sensor or the lack of a knock sensor. So I don’t get the attitude that menno must be confused and his observation wrong.
What do you think the odds are that 108k btu gas or less was included in the E10 when it was tested by the industry? I’d say zero.
As an auto industry technical professional, I am skeptical of claims that E10 results in a 10% increase in fuel consumption. These assertions are contrary to my experience and findings in highly controlled tests. It would be difficult to construct an engineering basis for such a claim, I know that.
You know, it’s not like E10 is anything new. Over 20 years ago it was widely marketed as “gasohol” and it has never really gone away. Unleaded gasoline invariably contains a signficant percentage of ethanol or something very much like it (ethers, butane, etc) as octane additives. The “pure gasoline” folks are talking about here does not exist, and it would be worthless in your car anyway. Generally speaking, the only reliable way to get “E0” (zero ethanol) gasoline is to order it from a fuel lab — which I have done on occasion in order to quantify the effects of ethanol blends in road use.
I can’t share the full results here as they are not my property, but Oak Ridge National Laboratory and others have conducted similar tests with similar findings.
http://www1.eere.energy.gov/vehiclesandfuels/features/int_blends_rpt_1.html
To cut to the chase, here is what E10 does in a late model (2002-on) passenger vehicle, averaged over a representative group of cars and light trucks in the North American market, in my experience:
Carbon monoxide: 14.8% reduction
Non-methane hydrocarbons: 10.0% reduction
Fuel Economy: 3.2% reduction
“It had 154 miles on the trip meter, trip computer said 37.9 mgp, the filler (running at the lowest flow /first click at the station near home) clicked off at 3.8 (US) gallons, so in line with my usual practice, I pushed another gallon in. I’ve never had gas on my shoes yet.”
With all due respect (simply trying to be helpful) that is a bad practice if you are trying to conserve fuel or measure fuel consumption with any accuracy. The extra fuel is mainly loading the car’s evaporative emissions system. Stop at the first pump shutoff, as generally specified in the owner’s manual, and recommended by virtually all consumer automotive authorities.
Thanks for the info, magoo.
Good input, Magoo. I know that my wife’s prior Hyundai Sonata, the 2002, couldn’t take more than an extra 5 cents worth of gas after the first click “off” while filling it up. But both of the Prius cars always have managed the extra gallon, taking the tank up to the 11 gallon limit rather than 10 gallons. Yes, the tank is that small. At the outset of owning the Prius, I would fill it to the first click on the pump then stop and once, I ran it to 1 green blob (out of 10) on the fuel gage and the tank took 10.9 gallons before clicking off (it was an oddity probably because I ran it so low? I dunno). I had obviously been running on fumes. After that I experimented and knew that I could get 11 gallons in; typically I go to about 1/2 tank on the gage then top it up 4 gallons and nurse the extra 1 gallon in.
My pal and his wife were over having supper and a movie tonight, and his family owns a gas station (in fact, a BP station). I told him about the Prius and the MPG loss and he said that 35% off the MPG for E10 is pretty much normal! He hears complaints about it all day long. Especially since BP were the last stations in the area to have non-ethanol polluted fuel, and “everyone” in the know was going to BP to get real fuel.
My experience with efficiency reductions is more between 6% and about 25%. My pal is a small engine mechanic and expert and he has NOTHING GOOD TO SAY ABOUT ETHANOL AS A MOTOR FUEL.
Experts can bleat all day long about “shouldn’t have any problems” and “only 3% to 5% efficiency loss is normal” but the people actually driving the vehicles and spending the money on fuel seem to have a different story.
Allow me to bleat further. The difference in energy content between E10 and so-called standard gasoline is around 3%. How then can it produce a reduction in fuel consumption of up to 25%?
If your test results vary from 6% to 25% going in, you have a faulty test procedure. You can’t say with any reasonable certainty what you are measuring, let alone what it might indicate.
No offense but gas station owners and small engine mechanics are not authorities on fuel chemisty and performance. If you of a mind to conduct a little science of your own and measure your fuel consumption, first you need a disciplined and consistent fill procedure. So far you don’t have one because you are overfilling the tank. That will account for the wild swing in measured consumption more than any variances in the vehicle or the fuel.
Once you have a consistent fill procedure — same pump, same fill level every time — then you need a test loop. You must cover the same route in the same approximate elapsed time or you are comparing apples to oranges. Only when your results are reasonably consistent can they be reliable.
You can’t say with any reasonable certainty what you are measuring, let alone what it might indicate.
Exactly right. The problem with these anecdotes is that we have no idea whether they are calculated properly or are actually comparable to one another. If you don’t fill the tank properly, don’t measure usage properly and don’t drive the same loop each time, then you can’t use these results at all.
The only way to test this stuff accurately is to do it in a lab, under strictly controlled conditions.
As I noted, I get the same kind of variation in my fuel economy as does Menno, even though I am buying fuel from the same service station, filling the tank in the same fashion, and measuring my usage as accurately as possible. The differences in my case are obviously not due to ethanol, because that’s a given in every instance.
At my work, one of the company cars (a BMW) just quit. Dead. When dragged to the BMW dealer, they tested the fuel and it’d had “excessive” ethanol in it. The car hadn’t visited the E85 pump.
One has to wonder if the extra 7 cents (or whatever) kick-back per gallon for adding an extra 10% ethanol to the gas is too much to resist for the oil companies.
20% ethanol in a non-flex-fuel vehicle obviously will void the warrantee. It’s also not legal.
But what the hell? Virtually nothing the government is doing now is legal, anyway; why should the oil companies behave any differently?!
I do have to wonder how much ethanol is really in the fuel. 20%? 30%? And by extension, how much WATER.
Magoo, Psych, I’ve tested all of my cars with care (and multiple times) over the years and can tell you that I do know how variances happen, and of course, my figures of 6% to about 25% (or, now, 34%) are outside of the lab.
But we don’t all live in the lab. I’m talking real life situation, here.
I’ll guess that The One will be pushing us to “legal” E20 before his first administration is out. We’ll be wondering how come a) our cars don’t run right and we get no MPG and b) our oil imports increase c) our dollar exports continue to increase and d) our money will decrease in true value and purchasing power. Of course, the additonal question for Joe Average with a car warrantee, is whether the auto companies will honor them (with mis-fuelling by E20) or not?
Don’t say I didn’t warn everyone!
“At my work, one of the company cars (a BMW) just quit. Dead. When dragged to the BMW dealer, they tested the fuel and it’d had “excessive” ethanol in it. The car hadn’t visited the E85 pump.”
I am VERY skeptical about that. Just because a car dealer says it doesn’t make it true. (You may have noticed this about car dealers.) First we need to know what is the dealer’s capability for analyzing ethanol content in fuel. Nil in virtually all cases. They can test for water and Reid vapor pressure and that’s about it. So how do they know it’s “ethanol damage”? You can’t tell by eyeball. What you mainly need to identify damage due to excess ethanol in a fuel is a predisposition toward that belief. On all reasonably current cars (1996-on) the fuel system components are validated up to E20.
“Magoo, Psych, I’ve tested all of my cars with care (and multiple times) over the years and can tell you that I do know how variances happen, and of course, my figures of 6% to about 25% (or, now, 34%) are outside of the lab.”
Variances of that degree are invariably due to the measuring regime. By definition. The car and the fuel are not changing in that magnitude, so what is? The driving route and regime, and the measuring methodology.
It is a fact that many consumers are not very good at monitoring their own mileage — or driving economically for that matter. Their findings are in large part impressionistic. That’s how utter frauds like the Tornado succeed in the marketplace. People find mileage improvements (or losses) for psychological reasons.
Typical driving scenario: driver starts car, warms up 10 min. Drives to the grocery store (4 miles) then sits outside ten minutes while wife picks up items, then drives back. Or sits in the Starbucks drive-through, any one of a hundred scenarios. But the point is: how many mpg do you get when the car is sitting still? Minus zero: the car is burning fuel but the odometer is not turning.
Obviously, this does not apply to your Prius with start/stop but there are still a number of other things that can skew your results. For one, overfilling the tank. First, the method makes it impossible to get the same fill every time. Next, it loads fuel into the evaporative system and there is no way to know how much.
“Exactly right. The problem with these anecdotes is that we have no idea whether they are calculated properly or are actually comparable to one another. If you don’t fill the tank properly, don’t measure usage properly and don’t drive the same loop each time, then you can’t use these results at all.
The only way to test this stuff accurately is to do it in a lab, under strictly controlled conditions.”
You make excellent points here. Even lab testing is to some degree arbitrary because it involves the construction of a virtual driving loop, which may or may not reflect an individual driver’s route and driving habits. This is the limitation of EPA/CAFE but any circuit/regime you can devise will have the same problem. Even if everyone drives the same (which they certainly don’t) Nebraska is flatter than San Francisco and that is just a fact.
All this said, the average consumer can measure his/her own fuel consumption with useful accuracy, but it requires some discipline and a consistent methodology — which includes knowing when a tankload will not be representative.
“Ethanol is playing havoc with the two carburetors on my boat, and these are not small engines. I pulled them off last weekend and they were all gummed up ( the boat ran fine in October).”
This is a documented problem with ethanol fuel blends in marine use. Many boats have used polyester resin in their construction, including fiberglass fuel tanks. (Poly is cheaper, quicker, and in general easier to work with than epoxy resin.) Ethyl and methyl alcohols absolutely will react with the polyester resin and the resulting gunk will migrate through the entire fuel system, gumming up everything. I’ve seen it and it’s nasty. The only reliable fix is to clean out the fuel system and redo the tank with epoxy resin.
Several weeks ago I wrote here that Shell premium, marketed as V-Power, is advertised as ethanol-free. Presumably Shell sells sufficient ethanol-contaminated regular and mid-grade to achieve the required Ontario 10-percent average.
Shortly thereafter I noticed the signs advertising Shell premium’s ethanol-free formulation have been removed. Shell assured me in an e-mail its premium grade gasoline is still ethanol free. Ominously, no explanation for the signs disappearing was offered.
Answer this: I have to go out of my way, but sometimes fill my Trailblazer with E20 at a blender pump. I get the EXACT same mileage as when I fill with E10. The last test was a 300 mile trip with E20 going and E10 coming back the same route.
npbheights comment “It is almost as if the ten percent ethanol has absolutely no energy content because I am getting about 10% fewer miles to the gallon with it.” can’t possibly be fact.
Also, my 1999 Honda Jet Ski runs great on E10 and always has.
Fritz said ‘I agree that as a country we need to move away from gasoline dependent locomotion. It is a national security and balance of trade nightmare.’
Ethanol is here and now. We all may have to make small concessions toward gaining energy independence and national security.
Please do your part.