I prefer the E-10 and have even run several tanks of E-85 thru the old girl. Ethanol cleans crap out of the fuel system and displaces water effectively as a bonus. Power loss and worse miles per gallon were undeniable on E-85 but when it was 40cents to as much as 60cents per gallon cheaper actual economy (as in dollars per mile) was not that bad. If I had E-85 available every where I would add a 6 or maybe even 8 degree trigger wheel and mill the heads for higher compression just for starters. My 20foot step van actually gets better economy on e-85 than on 87octane dinosaur fuel because the computer can adjust the fuel curve a little richer and advance the timing ALOT farther with out ping or having the knock sensor constantly backing it down. it is kinda an exception to the rule but you dont know unless you try it.