What are flex-fuel vehicles?

There are 19 million flex-fuel vehicles on the road in the United States, including 1 million in California alone. We’re going to venture out on a limb and guess that the vast majority of people who own those vehicles don’t know what “flex-fuel” means. So let us offer you a primer!

“Flexible fuel” vehicles can run on any combination of gasoline or ethanol, up to 83 percent (a blend called E85 … yes, we know that’s weird). The technology was made possible by the implementation of OBD-II, the second-generation on-board diagnostics computer system developed for cars in the early 1990s. The first mass-produced flex-fuel vehicle was the 1994 Ford Taurus.

More on the history of the ingenious technology from David Blume in our 2014 documentary PUMP:

As Blume, an expert in high-octane alcohol fuels, explains, an easy way to tell if a vehicle is flex-fuel is the yellow gas cap. Other telltale signs could include:

Badging on the rear of the vehicle (picture at right). Also, it might say “flex-fuel vehicle” or “E85” on the interior of the fuel door, and definitely in the owner’s manual.

If you’re still unsure whether the vehicle you’re driving (or want to drive) is an FFV, use our Check Your Car tool.

OBD-II’s sensors can tell what type of fuel the engine is running, and can adjust the timing (and other factors), based on the ethanol content. Higher ethanol blends have a higher octane rating than regular gasoline, so the computer brain accounts for that, maximizing efficiency.

For modern vehicles with parts that are compatible with ethanol, the only adjustment that would be needed is in the OBD-II software. Flex-fuel vehicles became all the rage a few years back, because automakers get special credits toward federal fuel-economy standards. Because the credits are weighted toward bigger “footprint” vehicles like pickups and SUVs, you see a lot of U.S.-made “Big Three” (Ford, FCA [Fiat-Chrysler], General Motors) vehicles that are flex-fuel. These are some of the most popular models on the road, including:

• Ford’s F-150 (as seen above, at the Orange County Auto Show last October) and Expedition
• Chevy’s Silverado and Suburban
• Dodge’s Charger and Ram 1500

Of course, not every model is an FFV for every year. Check out this useful guide created by Ethanol Retailer to see which 2016 makes and models can run on E85.

Although E85 is recommended only for FFVs, some people who drive OBD-II-equipped vehicles have converted their cars to optimize them for the fuel. Other drivers, with vehicles long past their useful lives, “splash blend” in some E85 to arrive at a level that suits their older cars.

So why use E85 at all? There are many reasons, but the biggest draw for the loyalists we’ve met is price: The fuel often is at least 25 percent cheaper than regular gasoline, which is enough to offset the drop in mpg you might see when running on E85. So you’ll have to fill up once or twice more a month, big deal. It’s a wash.

The hardcore E85 fans love it because it’s mostly not gasoline, which means supporting American companies and workers, instead of multinational oil companies and OPEC nations.

As a bonus, if one cares about such things, E85 is better for air quality and the environment — particularly cellulosic ethanol (often made from corn husks and other inedible plants), which carries less greenhouse-gas emissions than corn-based ethanol.

Don’t get fooled, go flex-fuel!

Related posts:

• It’s car shopping season. Consider an FFV!
• Not just corn: 10 homegrown feedstocks for ethanol
• Gas stations are adding E85, because it’s good for business
• This guy watched PUMP, got mad, sought out E85
• Hey Nebraskans, 1 in 10 of you drives an FFV