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Flex-fuel Vehicles

Flex-fuel truck

Flexible fuel vehicles (FFVs) are designed to run on gasoline or gasoline-ethanol blends of up to 85% ethanol (E85).1 Except for a few engine and fuel system modifications, they are identical to gasoline-only models. FFVs experience no loss in performance when operating on E85, and some generate more torque and horsepower than when operating on gasoline. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 15%–27% fewer miles per gallon when fuelled with E85.2

Find Flexible Fuel Vehicles…

FFVs have been produced since the 1990s, and more than one hundred models are currently available. Since FFVs look just like gasoline-only models, you may be driving an FFV and not even know it.

Do You Have a Flex-Fuel Vehicle?

Look for a Yellow Gas Cap or Fuel Filler Ring

Most manufacturers started putting yellow gas caps on FFVs as of model year 2008 (2006 for General Motors).

Yellow flex-fuel gas cap

Some capless fuel fillers have a yellow ring around where you insert the fuel nozzle.

Yellow filler ring

Check the Fuel Door

Some FFVs have labels on the fuel door indicating fuel type.

Flex-fuel label on fuel door

Check Your Owner's Manual

The owner's manual usually specifies which fuels can be used in your vehicle. If you don't have a manual, it may be available on the manufacturer's website.

Owner's manual

Look for Badges on Your Vehicle's Body

Badges with terms such as "E85," "Flex-Fuel," or "FFV" may indicate that your vehicle can use E85.

Flex-fuel badge Flex-fuel badge Flex-fuel badge

More Information

Fuel Economy Information for FFVs

Stations that Sell E85 (Alternative Fuels Data Center [AFDC])

Flex Fuel Cost Calculator (compare costs for operating your vehicle on gasoline and E85)

View Data Sources…
  1. Blends of 51%–83% ethanol can be labelled as E85 according to ASTM Standard D5798-11, "Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines," ASTM International, West Conshohocken, PA, 2003, DOI: 10.1520/D5798-11,
  2. The fuel economy difference between using E85 and gasoline is presented as a range since it depends on the ethanol blend and the vehicle:
    • The lower bound (15% mpg decrease) is based on the difference in the energy content of a 51% ethanol blend and that of gasoline, which is typically 10% ethanol.
    • The upper bound (27% mpg decrease) is based on the difference in official EPA fuel economy tests of recent-model FFVs operating on ethanol-free gasoline and operating on E85.

This website is administered by Oak Ridge National Laboratory for the U.S. DOE and the U.S. EPA.