Car Info
Everything You Need to Know about the E85 Flex Fuel Tech

Exactly what does it mean for you to use this ethanol-gasoline blend as your motor fuel?
Some cars these days allow you to use either gasoline or ethanol, or a mix of these two fuels, to run your car engine. This isn’t exactly new technology, since even the first Ford Model T (1908 to 1927) was actually a “flex fuel” car. It had carburetor jets that you could adjust to let the engine use an ethanol-gasoline blend.
Defining Flex Fuel Capacity
Simply put, flex fuel technology refer to the car components that enables the engine to burn an ethanol-gasoline mix as its fuel. This blend can contain anywhere from 15% to 85% anhydrous ethanol.
This flex fuel tech includes a special type of fuel-system plumbing, which can handle the more corrosive nature of the blend.
Also, the flex fuel system typically includes a built-in sensor which can figure out the exact mixture percentage of the blend. This has to be done in real time, so that the flex fuel system can then automatically adjust the engine ignition system to match the blend percentage.
Legally, any fuel marked as “E85” must contain an ethanol percentage within 51 to 85 percent. The precise percentage can vary, depending on your geographic location and the time of the year.
Differences When Using E85
At first glance, when you use E85 on your flex fuel engine, it doesn’t seem all that different than when you use pure gasoline. However, upon closer inspection you may notice certain differences.
One significant change is that your engine may give you somewhat great power when using E85, compared to when you use regular or even premium unleaded gasoline. That’s because E85 usually has a 110 pump octane number. With gasoline, that pump octane number is just 84 to 93.
The higher pump octane number for the E85 indicates its ability to handle more compression before auto-igniting. That means you’re able to run more spark advance, leading to more power from your engine.
On the other hand, you may end up sacrificing a bit of fuel economy and range. The E85 blend has only about 73% to 83% of the energy you can get from gasoline. So, your miles per gallon figures may drop by 15% to 27%.
Environmental Benefits
While some proponents of E85 brag about how the blend is better for the environment, this issue is a lot more complicated.
First, you need to understand that most of the ethanol used for blending with gasoline comes from corn. E85 supporters say that growing corn absorbs CO2, but then this is true even when American farmers were growing corn as a food or feed crop. When the corn became more widely used for alcohol blends, the worldwide CO2 absorption didn’t actually go up.
Growing corn also uses up a lot of water, and this water may be better used for food production. You also need a lot of energy to convert corn to ethanol. In fact, producing ethanol from sugar cane is actually more energy-efficient. Converting corn to ethanol takes 30% more energy in comparison.
Costs of Using E85
Because of the reduced fuel efficiency of using E85, you may find that you may end up spending more money for fuel when you put in this ethanol-gasoline blend in your flex fuel car.
Let’s say you drive your flex fuel car about 15,000 miles per year, using E85. About 55% of the time, you drive in the city while the rest of the time (45%) you’re on the highway. With these figures, you may spend $450 to $850 more on fuel per year.
Can Your Vehicle Use E85?
Back in 2015, there were actually about 80 different vehicles that were able to use E85. But in 2020, that number has significantly been reduced. According to the EPA, these models now only include the following models:
- Chevrolet Impala 3.6L
- Chevrolet Silverado 5.3L RWD, 4WD
- Chevrolet Tahoe/Suburban 5.3L RWD, 4WD
- Ford Explorer 3.3L AWD
- Ford F-150 3.3L V-6, 5.0L V-8, RWD, 4WD
- Ford Transit Connect 2.0L Van, Wagon
- Ford Transit T-150 3.5L RWD, AWD
- GMC Sierra 5.3L RWD, 4WD
- GMC Yukon/Yukon XL 5.3L RWD, 4WD
Some of these models are no longer in production, and they haven’t been replaced with an E85-compatible model.
Some brands indicate that their vehicles come with the flex fuel technology. But you can confirm this for yourself by checking the color of the gas cap or the cap-less filler neck. It’s compatible with E85 if its color is yellow.
E85 Availability
Different reports peg the number of E85 stations within a range of 3,300 to 4,800 spread out over 42 states. They’re so few because it costs $60,000 extra to install a special tank for the E85.
Most of the stations are located in Minnesota, Illinois, Michigan, Indiana, and Iowa. You won’t find any of these stations in Rhode Island, New Hampshire, Maine, Alaska, or Hawaii.
The Future of E85
Despite the political muscle of the Iowa corn growers lobby, the future of E85 looks bleak. Fewer cars are compatible with the blend, and it’s not especially beneficial for car owners or even the environment.
This is why some factions are now insisting that regular gasoline, which usually contains 10% ethanol, should switch to 15% ethanol. That still leads to poorer performance and fuel efficiency, however. All in all, flex fuel capacity for your engine just isn’t worth the trouble.