Originally Posted by Roadworthy
Here is an interesting idea:
Those who have a 2012 TI or I think virtually any 2013 that is designated as being able to use E85, I think they are tuned to scale better with higher octanes. E85 from my understanding has a much higher anti-knock rating, hence why people throw it in for race applications. The big requirement for engines to use E85 from what I remember is high pressure (Direct injection) and a tune that can scale the ignition timing higher to take advantage of the higher anti-knock properties, hence more power!
E85 is not particularly high octane. It's on par with 90-93 AKI octane rating fuel generally. Pure Ethanol has a higher octane rating, but most of the time they blend in sub-octane gasoline with E85 in order to lower the cost per gallon.
People use it for race applications because its cheaper than racing fuel, contains its own oxygen supply, and has a cooling effect as compared to E10 when injected into the combustion chamber due to the higher latent heat of vaporization.