The Inspector wrote:
An engine burning alcohol makes somewhere between high test gasoline but well below Nitromethane for power per specific unit, the advantage is the engine runs so cool from the alcohol they are difficult to get up to a good working block temperature which impacts engine effiency... Alcohol also suffers from very poor fuel economy and rapid evaporation which is in part why if your local car gas seller deals with E-85 you get much lousier mileage per tankful.
The cool running enhances charge density. Alcohol also has oxygen in it hence it needs to run richer than gasoline to achieve a stochiometric fuel to air ratio. That is also why you get "lousier" mileage. I don't think E-85 would run well in a carbureted engine unless you adjusted the jet size to compensate. Modern electronically fuel injected cars can adjust based on inputs from the oxygen sensor. Alcohol also has lower lubricity than gasoline and attracts moisture, so engine wear may be higher.
Of course using E-85 causes an increase in food prices because the grain is diverted from cattle feed, but that is a different thing altogether. They use a lot of alcohol fuel in South American countries I believe.