Ive never experimented with it, but I have held the belief that while in a modernly produced vehicle that there is going to be fuel economy losses with E85, I think they can be overcome. First and foremost would be to have a PCM that is tuned specifically to run E85. Better yet, have a PCM with two sets of programming in it. One for regular 87, 89, 91, etc and then one to run E85.

The second thing would be to up the compression substantially. The higher the compression the more efficient an engine is. So if you could take the compression up to say 11.0:1 or higher, Im not sure what E85 would support then I believe that you would negate the fuel economy losses or do so to such and extent it would be irrelevant.

Obviously on a supercharged engine the dynamics change a bit and Im not sure what you could get away with as far as compression. I dont plan on going with E85 at the moment but I should have a better idea of some other ideas I have once I get my engine back together that may shed some light on some other techniques that would allow much higher compression.