John writes:
I own an E92 M3 and it’s my huckleberry, except for one thing—with a gas tank capacity of about 16 gallons, road range is a measly 300 miles between fills. And when I drive, I want to drive.
Every other car I have owned has been able to do 400 miles on a single tank in highway driving with the exception of my STi, which only did 330 before rapid maneuvers caused temporary starvation.
So my question is this: is it possible to fit a larger gas tank to my car—say one of about 20 gallons or so? If so, what are the positives and negatives of this, and where would I get one?
Sajeev replies:
Back in the day, GM had you covered. Anyone remember the 36.5 gallon “Big Tank” option Chevrolet offered for the Corvette in the early 60s? Back here in Bimmer world, you have two opportunities for installing a 20-gallon tank in your M3. Only one is guaranteed to work.
I have never seen the underside of an E92, but I do recall the M3’s rear mufflers being pretty gigantic. Which means you remove them, run tiny mufflers (like Dynomax bullets) and route both pipes on one side. (Get some ear plugs too.) Only then will a 20-gallon fuel cell fit. Maybe.
If that’s out of the question, how in love are you with your trunk? That’s the only sure location for an E92 with a big gas tank. If either way is feasible, getting the tank is easy: any race shop stocks these fuel cells. Dimensions are readily available too. There are plenty of E92s set up for race purposes, and you will emulate their wiring/fuel pump/safety setups for your car. Not exactly easy, but it’ll be easier than you think.
P.S.: Doing an LS-X powertrain swap with the F-body’s 6-speed transmission (with that insanely tall top gear) might get you to the magic 400 mile mark. Think about it: that powertrain means you can idle at 55-ish MPH. That, and the V8 M3 will be disgustingly fast and light. So, again, LS-X swaps are still made of WIN.
[Send your technical queries to mehta@ttac.com]
I think he should count himself lucky to get 300 miles out of a single tank. I can only manage 250 from my miata.
Don’t do it.
You would have to consider what the added weight would do to your gas mileage and what that weight, up high and aft, would do to your CG and handling. You would have to assure it would be installed safely so it wouldn’t break free in a crash. Just think what your insurance company would think, and how your rates would be affected.
Hardly seems worth the effort. 300 miles is not that bad. The only vehicle I’ve owned which could exceed that significantly was an Astro with the optional 27 gallon tank, intended primarily for towing. Can your bladder last 300 miles?
Don’t know how you got 300 miles out of your STi.
I usually gas up @ 13 gallons and it shows 250-275’ish if I’m lucky. When I lived in the city it would be closer to 220. I can remember one time in the past 3 years I was over 300 before I gassed up…and that was about a month ago after I moved ~ 30 highway miles from work. I was at 315 and the low gas light hadn’t come on yet.
Anyway, consider yourself lucky. My primary commuter is a gsx-r and I’m lucky if I get over 160 on a tank (4.5 gal tank). With 0 miles driving outside of commuting, I’m gassing up 2-3 times per week (typically 5 times in 2 weeks). When I go riding on the weekends, it’s probably 3 times+/week.
At least the fill-ups are usually only $8-$10.
That’s an explosion waiting to happen. Come live in NJ, there are gas stations every 60 feet.
Oh, and the question is either a good joke, or proof positive that money and intelligence are not correlated.
I vote for a small harbor freight trailer with some fuel cans or a custom made tank for the trailer. Tire load range may be an issue… that and transporting fuel on the highway might be illegal but whatever you’ll have crazy range.
Run a couple of fuel lines to the trailer (this sounds dangerous) to your current fuel system (no way this could ever go horribly wrong) and you’ve got an instant super sized fuel tank (and the makings for a fireball only seen on the silver screen in an action flick).
The additional weight, plus carrying the weight higher is a BAD idea in a car so delicately balanced as your BMW. Anyway, why would any sane person spend that kind of money just to slightly extend the range?
Google Nascar gas cheating. Some good ideas there too. If you are going to mess up a perfectly good M3 so you can save yourself about 1 gas station stop per month, might as well go for broke.
Heh heh , swap in the drivetrain from a 86 528e. I gassed up in NY on I84 and drove ‘zactly 400 miles to Charlottesville VA on 13.5 gallons of regular. The Grape wasnt fast or pretty but it was a gas sipper.
What is with these little BMWs and their crappy mileage. German engineering! HA!
Just stop for gas more often. Between safety issues, packaging issues and weight distribution issues … you don’t really want to mess with it.
I feel your pain. I have a Honda Fit with a 10.9 gal tank. Same range. The best fix is a Ford van with a 35 gal tank and a Powerstroke diesel.
Just say no to straight pipes.
Typical M3 owner, need to nitpick everything to death. Would like to get 400mi range while hooning rather than 300. Really? You are driving the definitive sports sedan, just deal with it.
Is this a serious question? Your M3 is your “huckleberry”? Changing the fuel tank will likely void the car’s warranty and, probably compromise the emissions system, and will mess up the vehicle dynamics. Should you get in any kind of accident, it’s very likely your insurance company will successfully weasel out of any claim because the car has been modified. Not a good idea. More frequent pit stops must be the downside of M3 ownership.
Don’t mod the car. There’s no easy answer….although he was being (somewhat) facetious, Sajeev is correct in that his suggested powerttrain combo, especially with an unmodified LS1 or LS2 will easily give you 28- 30 mpg on the highway in 6th….pushing your range to well over 400 miles.
Odd how the “high tech,” “high specific output” 4 liter V8 in the M3 gets trumped in fuel efficiency by a 12 year old pushrod Chevy motor with more cubes and more torque. Oh, and that same motor is lighter, cheaper, and more compact than Bavarias finest.
The Mercedes-Benz 300SL Gullwing had a 34+ gallon (US) tank.
The BMW M3 is not a touring car.
You’ve got to be joking. Your going to mess with a perfectly good car because you want to increase your range to 400 miles?! My uncle had a truck in which he installed a second tank, but he used it for camping, where range is important, very important. One of the places I would go camping with my grandfather required us to bring along a 5 gallon can of gas to make sure we had enough to get back. In both of these cases, we’re talking about trucks that 10 mpg to 16 mpg on a good day and the standard 16 gallon tank just wasn’t going to cut it. Short of these very limited scenarios where you may actually need the range extension, just “put up” with stopping for gas every 300 miles like the rest of us and enjoy your car.
Just drink lots of coffee when you drive. Your bladder will take care of the rest. And, yeah, my answer is about as serious as the question.
Don’t mess with the stock tank. Have a second tank installed in the trunk per Sajeev’s suggestion if you must, but be aware that you’ll be adding 250 lbs off-center and at a high point in the chassis. The car will be slower in a straight line, slower to transition, and more prone to oversteer.
Just throw a few surplus steel jerry cans in the trunk, or fab some brackets and put ’em on the rear 1/4’s! Then have a solenoid valve to drain these into the stock fuel system. Ahh, no stopping. Mad Max style.
In my late model Mustang I get 280 miles to a tank if I run to empty, but I’m usually filling up every 220 to keep some weight over the rear tires. No big deal. To think some people buy their gas 10 or 20 bucks at a time; I always say they must love spending time at gas stations.
Get a standalone ECU or a tunable reflash. Take it to a reputable BMW dyno tuner and create a tune for efficiency and another for power. Best of both worlds. Then when you decide to boost it in a few years you ll be ready to go.
A properly installed racing fuel cell will be plenty safe. I don’t understand how you can hold your bladder for longer than 300 miles; I certainly can’t do it but I’m a coffee drinker.
Funny, as range was a main reason for not getting an M3 instead of a 335. Now it turns out the 335’s range isn’t great, either, if you step on it a bit. Makers of powerful cars need to stop expecting people drive them like EPA testers when dimensioning gas tanks. 0.1 gallon / hp, perhaps a bit less, would be a good starting point here out west.
if you live near a gas station which has got lpg I suggest you to convert it to gas/lpg . You should use system that inject lpg in liquid phase . Use a toroidal lpg tank and put it instead of spare tire .Congratulations , you have got almost double your range.
Actually, instead of the LS-X swap, which would be sacrilege, you’ll want to swap in the much more fuel efficient S52. I’ll provide everything you need and take the S65 and corresponding parts off your hands free of charge.
No, he is not a typical BMW owner, as he doesn’t want to stop at every other exit and “fill-up” in order to pose by his M3. ;-) Just kidding.
Man, I’m with some of the others on the questioning of wanting to drive more than 300 miles without a stop. Even if I had a gallon Ziploc for a bladder, I don’t have a callous for an ass.
My Dad used to hate to stop for us kids. I make a point to stop all the damn time now just as a matter of principle. At least once every 100 miles just to show my hinge what straight is again.
That, and the [LSX] V8 M3 will be disgustingly fast and light.
The bold part is correct. I know [hope] you joking say this, but I must rant anyway.
M models are supposed to be high revving, not high displacement. For as much as people blast certain cars for having no soul, it is strange that people are so willing to give up the soul of RX7s, Miatas, and even WRXs in the name of cheap power. The engine should fit the character of the car.
” Man, I’m with some of the others on the questioning of wanting to drive more than 300 miles without a stop”
Where there’s enough cars to support a gas station, there’s enough drivers to support a donut shop.
Quentin : The bold part is correct. I know [hope] you joking say this, but I must rant anyway. M models are supposed to be high revving, not high displacement.
Sort of, I only joke because the conversion is difficult for most everyone. But the character of the M3 is improved with a lighter, lower center of gravity, more efficient and abundantly faster power train. And there are plenty of LS-Xs that easily run to 7000rpm and are perfectly streetable…just look at the new Z06.
Citro, I know you’re kidding, but the M3 has no spare. I suppose you could fashion a tiny tank to replace the compressor/sealant kit, though.
To solve the weight distribution problems, just rip out the rear seats and put the second tank there. As a bonus, you’d gain enough room to add some kickin’ subwoofers.
so there is no spare tire in m3 , only a sealing kit – cheap bastards from bmw :)
I’m with the bladder brigade.
John, give yourself, much less your brakes, a few minutes to cool off… AT A GAS STATION.
Learn hypermiling?
I think you should trade in your M3 for a MINI Cooper S JCW. Smaller tank, further range, not quite as fast in a straight line, but much quicker and more fun in the corners.
“Oh, and the question is either a good joke, or proof positive that money and intelligence are not correlated.”
Yeah, that was my thought too. Anyone who would try to desecrate an M3 that way can’t be playing with a full deck. What the hell is wrong with stopping 100 miles earlier to get gas?
There are reasons you might want to drive 400 miles without stopping for gas-such as being a drug mule.
I like the angle on NASCAR cheats. One of my favorites was Smokey Yunick. When the size of the tanks were reduced in the 70’s Smokey managed to keep his car running as long as they did before the downsize. All he did was snake a bunch of one inch line around the car to make up for the missing five gallons. NASCAR hadn’t made any rules about the fuel line only the tank-until they caught the cheat.
Rspaight:
To solve the weight distribution problems, just rip out the rear seats and put the second tank there. As a bonus, you’d gain enough room to add some kickin’ subwoofers.
And if you asked, they’d probably offer you a sweet discount on a custom “LandauStyle” vinyl top.
I would imagine that even when you want to drive, you’re going to want to visit a bathroom somewhat regularly. 300 miles is probably farther than you’ll want to drive without stopping anyway – so why carry extra weight around with you?
And the person who brought a Mercedes SL into this discussion – sheesh. I own an old SL and yes, the gas tank is very large. That’s to offset the very thirsty engine and give it something like a reasonable range. Did I mention thirsty? I wonder if I could actually go 300 miles on a tank of gas? Do I care if I can? Nope.
Ahhh; little car, big engine, very competent chassis – lots of fun. But as wonderful as driving one of these is, it’s not for those who worry about how many MPG their car gets. And for those who have wondered – yes, it’s not only that good – it’s a whole lot better than you imagine.
Juniper :
August 13th, 2009 at 9:45 am
What is with these little BMWs and their crappy mileage. German engineering! HA!
4.2 liters isn’t exactly little in anyone’s book.
–
I’d say… get a propane conversion. Buy one of those toroidal tanks, fit it in place of the rear passenger seats.
Have the propane chip tuned to give you an extra 20-30 horses to make up for the speed lost due to the extra weight. Fun! (shameless alternative energy plug)
Enjoy your newfound 700 mile range. Run from the police for hours! Hold your bladder till it bursts!
But seriously… there doesn’t seem to be any easy OEM solution to this problem, as lesser marks of the 3-series have even smaller tanks… this is a “compact” car, after all… not a midsizer.
The only definite solution would be to replace the entire tank assembly, as Sajeev hinted, with a fuel cell… just keep the stock tank for warranty issues and eventual resale.
I’m not sure if anyone has mentioned this before but if the M3 has a spare wheel, (some cars nowadays don’t!) you could fit a reserve tank in the wheel well. I have seen this done for Liquified Petroleum Gas powered cars but not petrol ones. I’m sure the mechanics of getting the fuel out of the tank and into the engine would be much the same but it’s probably not worth it just to avoid filling up so often. In the UK, you need a special certificate to prove the work has been done properly.
A better bet would be to improve your driving skills and maybe fit low rolling resistance tyres. You could even have the ECU remapped for economy. These would be much easier ways of getting an extra 100 miles between fills.
At the end of the day, you bought an M3 not a Prius so what do you expect?
@ doctorv8
Odd how the “high tech,” “high specific output” 4 liter V8 in the M3 gets trumped in fuel efficiency by a 12 year old pushrod Chevy motor with more cubes and more torque. Oh, and that same motor is lighter, cheaper, and more compact than Bavarias finest.
Really? The BMW referenced weight with throttle bodies, all accessories and headers is 445lbs.
Various versions of the LS2 seem to be 450lbs onwards and it’s not clear if any accessories are counted.
niky :…this is a “compact” car, after all… not a midsizer.
There’s your answer–trade up to an M5. Surely it has a larger tank!