Sold by all U.S. vehicle manufacturers, flex fuel cars are capable of operating on gasoline, E85 (85% ethanol, 15% gasoline), or a mixture of both. There are more than 6 million flex fuel cars on U.S. roads today, but many flex fuel cars owners don’t know their vehicle is one.
What is a Flex Fuel Vehicle?
flex fuel cars are capable of operating on gasoline, E85 (85% ethanol, 15% gasoline), or a mixture of both. flex fuel cars qualify as alternative fuel cars under the Energy Policy Act of 1992 (EPAct). They also qualify for alternative fuel cars tax credits and can provide emissions benefits.
Unlike natural gas and propane bi-fuel vehicles, flex fuel cars contain one fueling system, which is made up of ethanol compatible components and is set to accommodate the higher oxygen content of E85. E85 should only be used in ethanol-capable FFCs.
Other than fueling capability and ethanol compatible components, FFCs are similar to their conventional gasoline counterparts. Their power, acceleration, payload, and cruise speed are comparable whether running on ethanol or gasoline. The only noticeable difference: fuel economy is lower when FFCs run on ethanol.
Many drivers aren’t even aware their vehicle is an FFC. To find out if your car is a flex fuel car, visit the National Ethanol Vehicle Coalition Web site.
Flex Fuel Vehicle Emissions
Using ethanol as a car fuel provides local and global benefits—reducing emissions of harmful pollutants and greenhouse gases.
Ethanol has been blended in low levels (10% or less) with gasoline for many years. This use of ethanol as an "oxygenate" promotes more complete combustion of the fuel, which can reduce exhaust emissions of carbon monoxide—a regulated pollutant harmful to human health—by 20% to 30% compared with pure gasoline.
Ford Expedition E-85
flex fuel cars fueled with E85 (85% ethanol, 15% gasoline) also emit less carbon monoxide than gasoline-powered vehicles. Emissions from E85-fueled FFCs of other regulated pollutants, such as hydrocarbons and nitrogen oxides (NOx), are similar to those from gasoline-powered vehicles.
Tests indicate that vehicles fueled with ethanol blends produce lower emissions of some toxic compounds—such as benzene and 1,3 butadiene—than vehicles fueled with pure gasoline. However, evidence suggests that ethanol might increase toxic aldehyde emissions.
In addition to exhaust emissions, all vehicles emit hydrocarbons due to evaporation of fuel from their tanks and fueling systems, especially in warm weather. The common oxygenate blend E10 (10% ethanol, 90% gasoline) has a higher vapor pressure than pure gasoline and thus produces higher evaporative emissions. E85’s vapor pressure is lower than gasoline’s, so it produces lower evaporative emissions.
Mid-level ethanol blends, such as E15 and E20, can be used in flex fuel cars but currently not in standard gasoline-powered vehicles. See the AFDC’s mid-level ethanol blends page to learn about emissions and other issues associated with these blends.
