Ethanol-based fuel, or E85, is an increasingly common alternative fuel that more vehicles can use instead of gasoline. The E85 name comes from the ethanol content, which is 85 percent (the remaining 15 percent is gasoline). An E85-compatible vehicle can run on a full tank of the E85 fuel, a full tank of gasoline or any mixture of the two.
Ethanol is a domestically produced fuel derived from biomass. In the United States, thatís mostly corn today, but technologies are being developed that allow ethanol to be made from a variety of plant sources, including grasses and other biomass by-products that donít impact food sources.
Although you may see more E85 pumps at your local gas stations, your car can use it only if it was designed for it. A yellow gas cap indicates E85 compatibility and itís important to never fill up with ethanol if your car wasnít designed for it.
Ethanol delivers about 70 percent of the energy of an equivalent gallon of gasoline, so the miles-per gallon performance when using E85 is somewhat lower than with gas.