If the addition of Ethanol Alcohol to gas actually deceases mileage then why do we use it, especially since the White House is calling for better mileage? Also when car makers give EPA for a car are the using 100% gas or gas with Ethanol alcohol?
Ethanol/gas mix provides less mileage but also less emissions (especially during winter). There are trade-offs with any fuel including: mileage, cost, availability, emissions, power, compatibility in current engines, etc.
There are many compounds that can be added to gasoline to increase its octane rating, and Ethanol is one of them.
The corn lobby is stronger than any other lobby except for the military industrial complex.