About one in seven Nebraskans is driving a flex fuel vehicle (FFV) and many don’t even realize it. A FFV can operate on any blend of American Ethanol from E10 up to E85 (85 percent ethanol) – and you can fill up with any blend in any amount at any time. A computer in the engine automatically adjusts for the varying percentage of ethanol in the fuel.nnTo see if your car is compatible with flex fuel, check your owner’s manual. Look for a flex fuel badge on your vehicle (usually on the truck lid, tailgate or rear quarter panel). You might also have a yellow gas cap or a decal inside your fuel door.