I was wondering, does 10% ethanol gasoline decrease gas mileage?

 

Yes, but not as much as a driver mod.

 

The more the ethanol the less the gas mileage.

 

But the trade off is you get a little more performance out of it. You won't notice the difference though because it's so little. The ethanol is how they blend in the oxygen to the gas which will help boost the octane and reduce knock according to a documentary I read. Some states actually mandate that gasoline be mixed with with 10% ethanol due to it burning cleaner.

 

most gas already has 10% in it. It might help a little with knock resistance if you tuned for it, but if you left your timing alone the only thing you would probably see fron it woud be slightly reduced milage.

 

There's no real octane gain from E10 gas because they use the ethanol to get to the target octane rather than other additives, if it's 93 it's still only 93 with E10 gas. The ethanol is about 30% less efficent as a fuel than gasoline, so you drop some mileage, but if it's less than 10% of the total you are talking 3-4% tops drop in fuel mileage, not enough to notice by itself.

 

So going off the ethanol use to achieve target octane, when the pump says up to 10% ethanol added on lets say 92, it could be potentially less than 92 octane since the ethanol content could be less than 10%?

 

The gasoline has to test at least a certain amount. Refineries add different chemicals to the base gasoline to get the desired octane for each level. If they can get to 93 octane by adding ethanol only instead of another additive, they will do that if it's cheaper. If the other pre-mix additive packages would have already raised the octane to the point that a 5% ethanol concentration is enough to hit the target and that route is cheaper, that's the way it will be.

You are almost guaranteed that you will get the right octane as they face fines for not doing that. As far as ethanol content is concerned, they admit right on the pump that it's "up to 10%", so you could be getting anything in that range.

 

Here ya go..... Ethanol-free gas stations in the U.S. and Canada Thats a website to find nearby pure gas stations. They are out there, but not many. Several years ago the push was to add ethanol to reduce our dependency on foreign oil. I found some Pure 91 and as an experiment filled up 3/4 tank ( had quarter tank regular 93 left) drove the same way I normally do. Thru the summer, I only occasionally get on it hard, maybe 3 to 5 times a week in the summer if that. I keep track of my mileage, and at that time I was averaging 30.9 mpg in a perfect half/half highway and light stop and go. The results astounded me. 34.9MPG. I'm certain if I had used all e free fuel, I would have surpassed 35MPG. It sure makes you wonder, add 10% E and lose 10+% MPG. Follow the money.

 

I can get about 10% more miles per gallon when I use non-oxygenated (ethanol-free) 91 octane gas, compared to 10% ethanol 91 octane gas. (35 mpg compared to 38.5 mpg) The biggest things that affect my daily commute are wind and if I use the AC.

 

The liberals who think adding ethanol to gasoline will make it burn cleaner are wrong. How can something that decreases your fuel mileage be considered "cleaner?" If you're burning more fuel, you're polluting more. God damn, liberals are such hypocrites.

 

leave politics out of this.

They are correct, oxygenating fuel causes a reduction in unburned hydrocarbons and CO emissions.

I dont buy the 10% less mileage claim, most states dont even come close to the E10, its up to 10% ethanol.

 

Then by that logic it exceeds 10%. I've filled up 5 times with the no E fuel and have noticed predictable results, 34. something each time, I was just using the 10% to arrive at my conclusion. Try some yourself and see what happens?