E85 gas is a blend of gasoline and ethanol with an ethanol content between 51 and 83 percent. Flexible fuel vehicles produced by foreign and domestic motor vehicle manufacturers use the fuel. Geography and the seasons determine the percentage of ethanol in the blend. Drivers using E85 fuel experience lower gas mileage than when using gasoline, because the fuel has less energy per gallon than gasoline does. Energy levels vary, and as the ethanol content decreases, mileage improves.
As of 2015, more than 2,400 public fueling stations in more than 40 states across the United States offer E85 fuel blends to more than 17.4 million FFVs using the nation's roads. Stations are concentrated in the Midwest. The Alternative Fuels Data Center website of the U.S. Department of Energy offers consumers an E85 Fueling Station locator and a vehicle cost calculator to compute FFV fuel costs, economy and greenhouse gas reductions. The Data Center offers consumers a fuel properties comparison tool to create custom charts that compare characteristics and properties of fuels, including gasoline, biodiesel and electricity. FFV drivers using E85 realize approximately 15 to 30 percent fewer miles per gallon than with gasoline.
In the 1990s, automakers began producing FFVs, which look just like gasoline-powered vehicles; more than 100 models are available. Since 2006, FFVs have yellow gas caps, or a yellow ring around the fuel nozzle entry point. The vehicle body may have an identifying badge such as FFV, E85 or Flex-Fuel.