the thing with E85 is that is has about a 105 octane rating...meaning higher flash point. thats why you see poorer gas mileage from it with these flex fuel cars that are made to run on 87. if you switch from 87 to 93 you will notice a drop in mpg aswell. that is probably the biggest factor there...but for 400hp, and to run nothing but E85, i think its very possible because you can run more compression and the E85 will cool the intake charge more than gasoline will and you have more room to play with before you get detonation..would be awesome for a turbo car..