than pump gas, making it more economical. That's not usually the case, but it's not especially rare, and I'd guess it will become more and more common as pump gas prices rise. I do the math using 30% since that's usually the higher end of the difference in mpg.
As for a real world example: Aaron's turbo FRS averaged ~32mpg on 93 octane. He gets 24-26mpg on E85. He has next to no highway driving.
BUT...you don't run E85 to save money. You just happen to occasionally.