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Javelin
Javelin SuperDork
9/13/11 5:32 p.m.

I've been trying to find different ways to increase the fuel mileage of the cars we have. Some of them work surprisingly well for basically no effort (proper air pressure in tires) and some have had minimal effect. One of the key issues I've found is the ethanol content and blend of gas being used. There's a lot of internet chatter about it, and there are some government reports (as if those are ever unbiased, one I keep seeing involves E30 and a 70's GMC dually that claims massive fuel increases), but what happens in a lab often doesn't correlate to the real world.

When we went to California to see my sister's baby (a 1,350 mile round trip) we drove each leg (down and then back up) over the course of 12 hours on 1 day, stopping only for gas/food/bathroom. Nearly the entire route was Interstate 5, a major road with 2-6 lanes each direction depending on where you are at. This was the perfect time to try and see if there was any gains to be had. The car was our 2006 Mazda5 with a 5-speed manual, ~76K miles on the digital odometer, and cruise control. We used cruise as soon as merged into traffic and checked the speedometer and odometer accuracy with the roadside markers and GPS app on the Droid phone.

On the return trip I was able to fuel up with an entire tank of ethanol-free 87 octane fuel in southern Oregon. The station and pumps were all clearly marked as ethanol free. All other fill-ups were at travel stop/truck stop stations with clearly marked "Up to 15% ethanol content" pumps. Same car, same driver, same road, same day. Yes, I know the elevation changes, and the weather changes, and blah-blah-blah etc. This was as close as I've been able to do on just straight 70MPH freeway shots. These are the results:

  • Tank 1 (E15): 267.9 miles, 10.364 gallons: 25.849 MPG
  • Tank 2 (E15): 269.6 miles, 10.446 gallons: 25.809 MPG
  • Tank 3 (E0): 124.6 miles, 4.101 gallons: 30.383 MPG

That's over a 15% jump in economy with no changes!

Obviously that's peaking my interest, as even at 20 cents per gallon more I would actually be spending less money. Now obviously, one tank does not a conclusion make (and yes, 2 tanks later it was back to exactly 25.8 MPG) but obviously there was something there. More testing needs to be done. Especially with stop-and-go rural/suburb driving.

Has anybody else done fuel testing with ethanol mix? What about octane mix? Can anybody even find another station with true E0 gas? It's a very interesting topic, with some pretty substantial monetary gains to be had. I don't want to start a stupid commenting war, I just want to learn and possibly help fellow GRM'ers (if it really does work).

So what say y'all?

iceracer
iceracer SuperDork
9/13/11 5:41 p.m.

Problem is, it is virtually impossible to find ethanol free gas any more.

aggravator
aggravator New Reader
9/13/11 6:02 p.m.

Where did you find E0 along I5?

mtn
mtn SuperDork
9/13/11 6:03 p.m.

I've noticed a decent spike in it. When I tracked it (at the time I was driving a 91 318) over three tanks each (E15 and E0), mixed driving each, it was about a wash in terms of price difference.

Javelin
Javelin SuperDork
9/13/11 6:13 p.m.

http://pure-gas.org/

Pacific Pride in Ashland. Website lists 92, but they have all 3 (87, 89, 92). The Pacific Pride's in general are pretty good. The one here in Longview has it as well. We also have an E85 station.

ransom
ransom HalfDork
9/13/11 6:35 p.m.

I thought Pacific Pride was one of those card-lock places you could only go if your company had a contract with them to fuel company vehicles...

I didn't realize they did retail. From the looks of their website, they don't.

Am I missing something?

Javelin
Javelin SuperDork
9/13/11 6:49 p.m.

I dunno, I don't have the receipts in front of me, it just sounded close. I'm pretty sure they have some branded truck stop/rest stop stores like the giant TA and Pilot's though. (Or maybe they are re-branded?)

Back on topic though...

I need to find a semi-convenient local E0 station to keep trying this. There's one close to my work in Vancouver, but all of the Longview ones are in the Industrial area.

ProDarwin
ProDarwin Dork
9/13/11 7:00 p.m.

I am curious to see the results or a longer more representative test (esp. after the brief argument/discussion in the other thread). Something like a 10-tank average with and without E15 would be interesting. Can you buy E0 where you live? Do you have any E10 tank data?

I'd do it here, but we only have E10.

wbjones
wbjones SuperDork
9/13/11 7:20 p.m.

without being as "scientific" as you were, I've seen my milage jump around in all 3 cars ( the '95 Impreza the least ...~ 2mpg) the Integra drops as much as 5 mpg and the Honda even more ...

like I said .. not scientific at all but on the same trips filling up at the same stations ( the big variable has been the weather) I've seen these differences .. and since the stations have signs that say " up to 10% ethanol" ... so I figure the only real difference is the amt of ethanol ....

Javelin
Javelin SuperDork
9/13/11 7:58 p.m.
ProDarwin wrote: I am curious to see the results or a longer more representative test (esp. after the brief argument/discussion in the other thread). Something like a 10-tank average with and without E15 would be interesting. Can you buy E0 where you live? Do you have any E10 tank data? I'd do it here, but we only have E10.

I'll gladly do a longer test, and I welcome others trying as well (in case it's just my car). We have E0 by one of my work locations, but that makes it a pain to track. I need to see if any of our local ones up here are easy to get to so I actually stick with it. Most of the gas here is E10, I'll try and remember to track my normal tanks for awhile so we can have that data as well.

Are we thinking like 10 of E15, 10 of E10, 10 of E0? Maybe 3/3/3 on all 3 cars (since they all have different generations of EFI)? I also wonder if the octane has anything to do with it. I know it's a # divided by a # and that those numbers are different depending on the blend, and then they equal out to 87. Does that sound right?

The funny thing about this test is I didn't even mean to do it. We were tracking mileage for the trip, but I didn't plan the fuel stops. We just happened to stop and the pumps said "Ethanol Free". I didn't even calculate the mileages until at least a week later (I wrote the odo and trip meter on the receipts).

Gearheadotaku
Gearheadotaku Dork
9/13/11 8:00 p.m.

Yes, pure gas will get you better mileage and more power. Here in Michigan, state law requires all pumps that contain Ethanol to be labeled as such, not sure if that's true on the federal level. As far as octane affecting mileage, try it for yourself. Every car's gonna be different to a degree. Had a friend with a later model Civic claim 1.2 mpg better with 92 vs. 87.

ProDarwin
ProDarwin Dork
9/13/11 8:25 p.m.

I'd do 10/10/10 in every car. Same pump for each set of 10. Yeah, it will take a while. If a bunch of people here could contribute it would certainly help.

I know I'm tempted to do an "additive" test, as on 3 different occasions I logged 42mpg highway when I put in a bottle of injector cleaner. It was weird.

NGTD
NGTD Dork
9/13/11 8:58 p.m.

Ethanol has lower energy content than gasoline, so as long as you reach the octane level without it, and your car runs with that octane level without pinging, then E0 should always give better mileage than any ethanol mix.

I know on a number of Subaru boards around here, tuned WRX's have been reported as getting better mileage and power on Shell 91 than they do on Sunoco Ultra 94 because it has lower ethanol content eventhough it is 3 points lower on octane.

Zomby woof
Zomby woof SuperDork
9/13/11 10:07 p.m.

Shell seems to be playing a little game with the ethanol/no ethanol thing. Depending on who and when you ask, they either have it or they don't. They also have claimed to be both ethanol free and top tier at the same time.

Hocrest
Hocrest HalfDork
9/13/11 10:28 p.m.

Not very scientific, but I used to see a 5 - 10 mpg bump in my SVX when the station near my old house had E0.

I'd love to try it and track mileage, but according to pure-gas, the closest station is about 2 hours from here

MitchellC
MitchellC Dork
9/13/11 10:48 p.m.

Back before ethanol blends I would get 25-28 mpg in the Focus SVT, with 66/37 city/highway. I now drive almost strictly city, and with ethanol gas, I barely get 20. Not too great for a little hatchback!

novaderrik
novaderrik Dork
9/13/11 11:30 p.m.

the only real testing i've done has been in my 84 T Type and 97 Cavalier..

the best fuel mileage my T Type has ever seen was one magical interstate trip where it got 24mpg on a full tank of straight E85.. it usually only gets 14mpg on E85, and 17-18 on any blend up to 50% ethanol.

my 97 Cavalier got the same mileage on up to 50% ethanol as it did on 87 octane E10, but anything more than 50% would see the mileage drop from almost 40mpg down to the low 30's. i can't remember the last time i had gas without ethanol in it in any of my cars- but it was probably my Nova in the 01-02 time frame. i don't recall getting any better mileage on then on oxy than on regular 89 octane E10 gas, but i also didn't really religiously check the mileage on that car, either.

Joshua
Joshua HalfDork
9/14/11 12:09 a.m.

I usually run 91 with ten percent ethanol added, I got 37.8 MPG in city, in my Miata, but I hyper-mile so it's not really relevant.

HiTempguy
HiTempguy Dork
9/14/11 12:20 a.m.
Zomby woof wrote: Shell seems to be playing a little game with the ethanol/no ethanol thing. Depending on who and when you ask, they either have it or they don't. They also have claimed to be both ethanol free and top tier at the same time.

AFAIK, regular is up to 10%, silver is up to 5%, and premium is 0%. That's how they get it to average out to meet the 5% federal rule. I know for a fact that their premium is ethanol free though!

Zomby woof
Zomby woof SuperDork
9/14/11 12:34 a.m.

That varies by province, and people here say the same thing. Try to find out for sure if it's true though. The point is, if you're going to try different fuels, know what you're getting.

Travis_K
Travis_K SuperDork
9/14/11 1:15 a.m.

Both a 1996 legacy and 1992 jetta seemed to average about 2-3 mpg less on e15 (costco), and my Milano had a fuel leak after running it for one tank. The observations are true, I'm not sure if they have much meaning though.

Curmudgeon
Curmudgeon SuperDork
9/14/11 7:11 a.m.

I'm pretty anal about watching the fuel mileage on the fleet. Casper the (carbureted) JH5 has always gotten about 21 regardless of what type liquid gold I run in him. Tucker the (fuel injected) Trooper showed an immediate ~8% drop in mileage when E10 became the only game in town. That wasn't nearly as bad a drop as when the thermostat seal split meaning the engine never warmed up, that was a nearly 18% drop. No that's not a fatfinger.

dark1911
dark1911 New Reader
9/14/11 9:05 a.m.

In my pickup truck, I went from 22mpg to 17just mpg. I wish I could find real gas again.

iceracer
iceracer SuperDork
9/14/11 9:06 a.m.

I read somewhere one upon a time that there was an easy,do it yourself way to check for the amount of ethanol in the gas. anybody know ?

wbjones
wbjones SuperDork
9/14/11 3:44 p.m.
Gearheadotaku wrote: Yes, pure gas will get you better mileage and more power. Here in Michigan, state law requires all pumps that contain Ethanol to be labeled as such, not sure if that's true on the federal level. As far as octane affecting mileage, try it for yourself. Every car's gonna be different to a degree. Had a friend with a later model Civic claim 1.2 mpg better with 92 vs. 87.

I've been told that it's a federal law... but it's up to the states to enforce ... here in NC, it's not enforced.... if it says 10% then yeah... if no sticker, you're on your own

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