Originally Posted by PNA

Part of that is the lower energy value of ethanol, but not necessarily all of it. You would likely get anywhere from 10-30% reduction. If you were gettting 220 (low end) and now 280 (high end) your mpg on the new fuel is about 3.8 mpg higher with E0. That's just under 30% reduction, which is in line with the high end of the expected reduction based on the ethanol.

I have to say, my XFire get's significantly better gas mileage than that. I don't have an SRT6, and I don't drive it agressively (at least not all the tiime) and I've been getting between 22 and 26 mpg -- and I drive in the worst traffic in the country -- and I know I'm using E10. I guess I should be pretty happy with that.

Just be informed, E10 is in about 90% or more of all gasoline now and likely will be in all of it very soon. It may go higher as well -- up to E15.