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What is Flex Fuel?

By Autolist Staff | October 22, 2018

'Flex-fuel' is short for flexible fuel; vehicles that use flex fuel are designed to operate with a mixture of gasoline and ethanol or methanol. Since many new vehicles today run on fuel that contains some amount of ethanol, those denoted as 'Flex Fuel' are different because they operate with as much as 85 percent ethanol mixed in. This is known as the E85 blend.

What Are Ethanol and Methanol?

Other than gasoline, ethanol and methanol are the prime ingredients in flex fuel.

Pure ethanol is essentially grain alcohol and it is primarily made from corn in the U.S. Touted as being cleaner than gasoline, ethanol burns cleaner and with less carbon monoxide than gasoline. It also burns more fully than gasoline, which means overall fewer emissions.

Methanol is also known as wood alcohol and methyl alcohol. It is produced through the destructive distillation of wood and is generally less popular than ethanol as a fuel additive.

Benefits of Vehicles Using High Ethanol Fuel Mixtures

Flex fuel advocates argue that these engines use cleaner-burning fuel and emit fewer toxic fumes into the atmosphere.

Flex fuel vehicles are also intricately designed with electric sensors that detect the blend of fuel and adjust accordingly.

So the combustion chamber could contain anywhere from 10 to 85 percent ethanol and the vehicle's technology will automatically use it as efficiently as possible.

As an alternative to oil, ethanol is sustainably produced mainly from corn and sugarcane, which helps reduce dependence on foreign oil. Some municipalities offer a tax credit on some flex-fuel vehicles, which can help lower an individual or business tax obligation.

Downsides of Flex Fuel Vehicles

There are some disadvantages to using high mixtures of ethanol in flex-fuel vehicles. One of the main disadvantages of using ethanol is that the crops used to produce it can only be used for that purpose. Corn crops require a lot of labor, and producing corn solely for fuel can lead to higher prices for the crop in other markets.

High ethanol blends are also known for causing engine damage after prolonged use due to the way ethanol absorbs dirt. This dirt eventually corrodes and damages engine parts.

Ethanol does not get the same level of fuel economy as gasoline and there are far fewer stations that supply ethanol across the country. Some estimates show that flex-fuel vehicles using the E85 blend get as much as 15 percent less fuel economy compared to gas alone. This is problematic due to the higher standards for fuel economy currently imposed by the EPA.

The Future of Flex Fuel

Despite the downsides, ethanol's popularity as a fuel mix is still growing and more refining plants are coming online. As of 2017, ethanol was no longer in the research phase and it still has the potential to be the first alternative fuel with national backing.

However, more research needs to be conducted on the viability of the crops used to make the fuel and the environmental impact therein. Ethanol can technically be produced through the fermentation and distillation of any starch crop and most commonly these are corn, sugarcane and potato.

Flex Fuel Gas Mileage

Most experts agree that flex fuel is likely to decrease the gas mileage of a vehicle using it. Ethanol raises the octane level of a vehicle slightly, which would, in theory, improve gas mileage. However, ethanol has less energy than gasoline, which means that about 1.5 times more ethanol is needed to have the same energy as gas.

Ultimately, some research shows that this results in similar gas mileage while other research has ethanol coming up short. For the consumer, it's worth remembering that ethanol typically costs less than gasoline, so the expense of reduced gas mileage could potentially be mitigated.

It's also worth noting that ethanol is routinely added to the fall/winter blends of regular gasoline for non-flex fuel vehicles to raise octane.

Finding and Pricing E85 Fuel

At the time of publication, the average national price of E85 was about $2.17 per gallon, according to E85prices.com. That compares to $2.81 per gallon for conventional gasoline.

Finding gas stations that sell E85 is relatively easy. Most of the major brands, including Shell and ExxonMobil carry E85 gas. Searching on the Internet for flex fuel stations or E85 stations also produces several sites dedicated to mapping and locating gas stations that sell high ethanol blends.

When shopping for a flex-fuel vehicle, the main indicators are a yellow fuel cap, the E85 sticker or another logo or sticker marking the vehicle as flex-fuel capable.