What is Flex Fuel?

Asked by Dec 15, 2017 at 02:36 PM

Question type: General

2 Answers


It's E85 fuel, a gasoline-ethanol blend of up to 85% ethanol. Vehicles designed to run on it will usually be badged as "FFV" (flex fuel vehicle) or "Flex fuel". It's cheaper gas, but the trade-off is worse gas mileage. AFAIK any E85 vehicle also runs most other types of gas as well, making E85 an option.


Ethanol blended gasolines are available from E-10 to E-85. 10 is 10% ethanol and 90% gasoline the 85 is 85% ethanol and 15% gasoline. For anything over E-15 to be properly used in a vehicle it should be a flex fuel vehicle. Those usually have a yellow gas cap or written indication that it is a flex fuel vehicle somewhere on it. As KenF stated E-85 is cheaper, but you will use more of it cause it has less energy content than plain old gasoline. E-85 does have a higher octane rating so a small boost in performance is possible using it in the correct type of vehicle. Do some reading at the link...https://www.fuelfreedom.org/what-are-flex-fuel-vehicles/

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