E85 has never penciled out when I've looked at it in the past, but as another forum member pointed out things have changed lately. E85 is currently ~40% cheaper than E10
E85 btu: 81,860 (28.5% lower than pure gasoline)
E10 btu: 110,660 (3.4% lower than pure gasoline)
Gasoline btu: 114,500
I wouldn't count on that trend holding long term, but it kind of makes me want a plug-in hybrid flex fuel vehicle for maximum flexibility in times of volatility...