Flex Fuel Vehicles (FFVs) are designed to run on E85, 100% gasoline, or any combination in between. So, if you have a half tank of regular and want to fill up with E85, there’s no problem.  A special sensor in the FFV determines the ratio of gas to ethanol and adjusts the ignition timing and fuel flow rate for whatever mixture is in your tank.

The special components in FFV fuel systems allow them to run on mixtures of ethanol and regular unleaded gasoline up to an 85% concentration of ethanol.  Other than these special fuel system components, FFVs look and drive just like regular gasoline-only vehicles. 

Remember that E85 can only be used in FFVs.  For a listing of FFVs in the state fleet, click here.  Not all vehicles of any make and model listed are FFVs.  Be sure to check inside your fuel tank cover for a sticker that says “E85” or “Ethanol Fuel.”