E85 and E15 are alternative fuels made up of a mixture of gasoline and ethanol. Primarily made from corn, ethanol-based fuel blends burn cleaner and emit less carbon monoxide than standard gasoline blends. E85 contains up to 85% ethanol and is intended for use by Flex Fuel Vehicles. (To determine if you have a Flex Fuel Vehicle, look for a decal inside the fuel door of your vehicle). E15 contains 15% ethanol and can be used by any car 2001 or newer.