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2015 Toyota Prius v - Flex fuel?

Is it OK to use E15 gas in my 2015 Prius, as I have been for a year or so? The pump used to say it was OK for cars manufactured after a certain date in the 1990’s. Now it says for flex fuel cars only, and that it is a federal crime to use it in other vehicles. What, exactly, is a flex fuel vehicle?

Flex Fuel vehicle can run up to 85% alcohol in the gas. Your owners manual will tell you what fuel is safe to use in your vehicle. Remember the greater the ethanol percentage the lower the miles per gallon.

The cow is pretty much out of the barn isn’t it? You have been doing this for a year and now you ask the question.

Open your owners manual, look up “fuel” and read what it says about E10 - normal car fuel with 10% ethanol and E15 - fuel with 15% ethanol and if it says anything about E85 or flex fuel with 85% ethanol.

If it doesn’t say you can use E15 or E85, you can’t.


I suspect that sticker got applied to the wrong pump handle or button (E15 instead of E85).

As others have said, you should have checked your owner’s manual a year ago.

E15 gas is NOT flex fuel.

Flex Fuel has much higher Ethanol content.

The flex fuel cars in our family fleet (GM vehicles) have a placard reading “flex fuel” at the filler opening. Even that back of the cars, on the trunk, say it.

The information is on page 560 of the owners manual;

“Use only gasoline containing up to 15%
DO NOT use any flex-fuel or gasoline
that could contain more than 15% ethanol,
including from any pump labeled
E30, E50, E85 (which are only some
examples of fuel containing more than
15% ethanol).”


To be clear, no fuel is “flex fuel.” Flex fuel is a vehicle standard that indicates the car can run on gasoline, pure ethanol, or any combination thereof.


Correct. Vehicles that are Flex Fuel can use the E85. We have a lot of pickups and large SUV’s around here that are Flex Fuel rated, but E85 gas isn’t sold here.


Right, there is no “flex fuel”, there are flex fuel vehicles. A car that must use E85 (some race cars) is not a flex fuel vehicle.
You could regard modern oxygen sensor feedback EFI as semi-flex fuel (and flex altitude), it’s just that the range is limited to E0 to E10.

using E85 will lower you fuel mileage by about 30%. E15 probably is a tic lower mileage than E10

Pretty sure no Prius is a flex fuel vehicle.

The ultimate flex fuel vehicle is an electric car. Coal, wind, nuclear, natural gas, hydro, and even solar.


Good point


Except terminology distinctions are important. Flex fuel refers only to gas and ethanol mixed, not random different fuels.

For instance, technically if I install a jet engine in the back of my car and keep the original engine, I’ve got a “hybrid.” But that doesn’t mean I should qualify for hybrid tax and registration discounts, and so it’s important to write those laws specifying that a hybrid is a dual-motor car with one gas and one battery-powered electric motor.