Check this out....http://www.gm.com/company/onlygm/fuel_flexible.html

E85 FlexFuel Vehicles operate on a blend of 85% ethanol and 15% gasoline. Good news, because for every 37 gallons of E85 ethanol used, you're saving one barrel of oil-- reducing our dependence on petroleum. E85 ethanol, a renewable fuel made from U.S. grown bio material (like corn or grain products), also helps reduce greenhouse gas emissions. GM has more than 1.5 million FlexFuel Vehicles on the road today in all 50 states. Together we can:

Take advantage of the choice between gas-powered vehicles and cleaner, E85 ethanol vehicles
Reduce our dependence on petroleum
Reduce carbon dioxide emissions
Gain increased horsepower for better engine performance because E85 ethanol fuel has a higher octane rating than premium gasoline
Lessen engine wear