I have seen many write ups where folks take the "Pepsi Challenge" on Flex fuel vehicles with E10 vs E85. The numbers I have seen thrown around is that E85, gallon for gallon, produces 25% less energy than E10, while costing 10% less (than regular) so you don't win with E85. But if you are running high compression or a boosted engine, I doubt hypermiling is in your 5-10yr plan in the first place :thumbsup:
you are making big numbers, very impressive, but detonation is detonation, doesn't matter if it's from E10 or E85, you can easily hurt the motor. Kind of like the old saying "Friendly Fire isn't"