E15 MPGs

Anyone else running this? I got stuck once because the other pumps were out and was surprised to see my normal 17/18 mpg number bump to 19 mpg. After 4 tanks in a row, I'm still seeing these numbers consistently.

Not looking to start another "I only use rocket fuel" debates, just curious if anyone else runs this and sees positive results. Seems to go against reason, but it looks like I am getting better mileage with fuel that runs .10 gal cheaper.

 

Doesn't the fuel cap, owners manual, and Toyota say not to use E15+?

 

Looks like you can use up to E15 but no higher.

 

E15 you can use. It's E85 that you can't. Basically the opposite. E15 is 15% ethanol, E85 is 85%.

What I find odd with my improved mileage is that in theory, there should be less energy resulting in worse mileage. I'm seeing the opposite. Now I also realize that an internal combustion engine is on 20-30% efficient and the vast majority of the gas we burn turns into heat and goes out the exhaust, so maybe my motor is getting better efficiency with a fuel with less energy?

 

I could have sworn it was 15+ but I guess I was wrong

 

My gas cap on my 18 shows 20+

 

When I first got my truck I experimented between 3-4 tanks of E15 then 3-4 tanks of non-ethanol. Neither one was any better or any worse than the other.
Could be where you're at it could just be at the point where it's switched from winter to summer gas? I always get 1-2 mpg's better on summer gas.

 

Ethanol has less energy than gasoline so theoretically your mileage should drop. Perhaps the additional ethanol allows the gas to burn more efficiently; however if that were so, there would no doubt be campaigns to promote more corn. In any case, let us know how it goes, assuming that you plan to continue to use the E15.

 

Ethanol has about 70% the energy of gasoline, so E15 would have about 95-96% the energy of pure gas.

All else being equal, that would mean you'd theoretically get 19 mpg on E15 if you got 20 mpg on pure gas. Don't know about you, but my mileage varies way more than that just based where I'm going, or length of trips, etc.

How's the weather there? It just warmed up a lot around here, and those cooler mornings are no longer sucking gas mileage as the truck warms up (this is a huge factor I see, don't know about you).

 

Ethanol, I believe, acts as an octane booster. The knock sensors may have noticed and advanced the timing accordingly. Generally advanced timing means more power (up to a point obviously). Really though - beats me!

What octane do you usually run and is it Top Tier gas?

 

I thought about that. I typically use 87 and e15 is 88, but in the past I have used 89 and 91 with no difference at all.

Thought about that as well, but I never have gotten anywhere close to 19 with the switch (I'm not really sure they switch in Florida). I get a consistent 17.5/18 year round. I have wondered about non ethanol. The price has held me back from trying it. It runs about $1 per gallon more around here. Hard to justify and extra $20 for a fill up. It would have to get me 30 mpgs to justify that!

 

Any vehicle made after 2001 is legally required to be able to run 88 octane (E15) fwiw. OP seeing better gas mileage with 88 is very interesting. I've run it a couple times with no discernable mpg difference. Might need to try it again now!

Oddly, I find I get worse MPG when I run 93 through my truck than normal 87. Stock tune.

 

That's the truck just pissing you off because it costs more.

 

Is it bad to use E15? I have always shied away from it because it is only a nickel or so cheaper but every once in a while E85 is super cheap.