What Is Flex FuelFlex fuel refers to a vehicle engine designed to run on more than one type of fuel blend, most commonly regular gasoline or E85, a blend containing up to 85 percent ethanol. Flex fuel vehicles, often marked FFV on the dash or fuel door, can switch between these fuels with no modification needed, since the engine computer automatically adjusts based on whatever is actually in the tank.E85 vs Regular GasolineE85 usually costs less per gallon than regular gasoline, sometimes by 50 cents or more, but it also carries less energy per gallon, which typically lowers real world MPG by somewhere around 15 to 30 percent. That efficiency gap means the lower price at the pump does not automatically translate into a lower cost per mile, and in many cases the two fuels end up costing roughly the same to actually drive on, or E85 even comes out slightly more expensive depending on the local price gap that week.A Quick Example of the TradeoffPicture a flex fuel vehicle that gets 25 MPG on regular gasoline at 3.60 dollars a gallon, working out to about 14.4 cents a mile.
The same vehicle on E85 might drop to around 19 MPG, but if E85 is priced at 3.10 dollars a gallon, the cost per mile actually rises slightly to about 16.3 cents a mile, despite the lower price at the pump. The only way to know which fuel is genuinely cheaper for a specific vehicle is to compare the real cost per mile, not just the price per gallon.How to Know If Your Vehicle Is Flex FuelCheck the fuel door or the badge on the rear of the vehicle, which often reads flex fuel or E85 directly, or check your owner's manual if neither is visible. If you are unsure whether switching to E85 would actually save you money given your specific MPG difference between the two fuels, running both gas prices through the Fuel Savings Calculator gives you a clearer answer than the pump price alone.Wondering if E85 is actually cheaper for your specific vehicle?
Compare both fuels with the Fuel Savings Calculator.
Frequently Asked Questions
Is E85 always cheaper to drive on than regular gas?
Not always. While E85 usually costs less per gallon, it also lowers MPG, so the actual cost per mile can end up similar to or even higher than regular gasoline depending on the local price gap.
Can I put regular gas in a flex fuel vehicle?
Yes. Flex fuel vehicles are designed to run on regular gasoline, E85, or any blend in between, with the engine computer adjusting automatically.
Does flex fuel hurt engine performance?
E85 generally provides similar or slightly different performance characteristics rather than hurting the engine, since flex fuel vehicles are specifically engineered to handle the different fuel properties safely.
Why isn't E85 available everywhere?
E85 requires specific pump and storage infrastructure that many gas stations have not installed, so availability tends to concentrate in regions with stronger ethanol production, particularly parts of the Midwest.