E85 is the designation for a fuel that combines 85 percent ethanol with 15 percent gasoline. E85-compatible—or flex-fuel—vehicles can run on E85 or regular unleaded gasoline. Because the alcohol in E85 can break down rubbers and plastics used in typical internal-combustion engine fuel systems, vehicles must be specially modified to allow its use. And to obtain maximum power from higher-octane E85, engines must be tuned to run on it, or be able to adjust timing and the air-to-fuel ratio when running on E85.
Supporters say the alternative fuel is environmentally friendly, reduces dependence on fossil fuels and imported oil, and takes advantage of America’s surplus of agricultural crops, like corn, that can be readily converted to ethanol for use in E85.
Critics note insufficient ethanol production facilities exist to significantly offset the nation’s appetite for fuel, that refineries aren’t adapted to producing E85, and that E85 is harder to transport because its corrosiveness means it cannot flow through existing gasoline pipelines. In addition, in most states E85 costs about the same as unleaded regular while costing the driver up to 15 percent in fuel-economy penalties because it does not pack the same explosive punch as gasoline.