What race cars run on alcohol?

Ethanol Benefits and Considerations

Ethanol is a renewable, domestically produced transportation fuel. Whether used in low-level blends, such as E10 (10% ethanol, 90% gasoline), E15 (10.5% to 15% ethanol), or E85 (flex fuel)—a gasoline-ethanol blend containing 51% to 83% ethanol, depending on geography and season—ethanol helps reduce emissions. Like any alternative fuel, the use of ethanol involves several considerations.

Energy Security

The United States became a net exporter of petroleum in 2020 with exports surpassing imports, although imports of 6.11 million barrels per day remained an important part of balancing supply and demand for domestic and international markets. Overall, the transportation sector accounts for approximately 30% of total U.S. energy needs and 70% of U.S. petroleum consumption. Using ethanol and other alternative fuels and advanced technologies to reduce fuel consumption continues to strengthen national security and reduce transportation energy costs for businesses and consumers.

Fuel Economy and Performance

The impact to fuel economy varies depending on the energy difference in the blend used. For example, E85 that contains 83% ethanol content has about 27% less energy per gallon than gasoline (the impact to fuel economy lessens as ethanol content decreases). FFVs are optimized for gasoline. If they were optimized to run on higher ethanol blends, fuel economy would likely increase as a result of increased engine efficiency.

Ethanol also has a higher octane number than gasoline, which provides increased power and performance. For example, Indianapolis 500 drivers often fuel their race cars with E98 because of its high octane. The Co-Optimization of Fuels and Engines initiative researched the potential to improve engine efficiency through the use of ethanol blends and other high-octane biofuels.

Job Impacts

Ethanol production creates jobs in rural areas where employment opportunities are needed. According to the Renewable Fuels Association, ethanol production in 2021 accounted for more than 73,000 direct jobs across the country, $52.1 billion of the gross domestic product, and $28.7 billion in household income. (See the 2022 Pocket Guide to Ethanol.)

Emissions

The carbon dioxide released by a vehicle when ethanol is burned is offset by the carbon dioxide captured when the feedstock crops are grown to produce ethanol. This differs from gasoline and diesel, which are refined from petroleum extracted from the earth. No emissions are offset when these petroleum products are burned. On a life cycle analysis basis, greenhouse gas (GHG) emissions are reduced on average by 40% with corn-based ethanol produced from dry mills, and range between 88% and 108% if cellulosic feedstocks are used depending on feedstock type, compared with gasoline and diesel production and use. (See the Life-Cycle Greenhouse Gas Emission Reductions of Ethanol with the GREET Model.)

To learn more about fuel economy, GHG scores, and U.S. Environmental Protection Agency smog scores for FFVs, visit FuelEconomy.gov, or see the Alternative Fuel and Advanced Technology Vehicles list.

Equipment and Availability

Low-level blends of E10 or less require no special fueling equipment, and they can be used in any conventional gasoline vehicle.

It is also possible to accommodate blends above E10 in existing fueling equipment, however, some equipment needs to be upgraded to comply with federal code. See the Codes, Standards, and Safety page and the Handbook for Handling, Storing, and Dispensing E85 and Other Ethanol-Gasoline Blends for detailed information on compatible equipment.

FFVs (which can operate on E85, gasoline, or any blend of the two) are available nationwide as standard equipment with no incremental cost, making them an affordable alternative fuel vehicle option. Fueling stations offering E85 (flex fuel) are located in 44 states. Find ethanol (E85) fueling stations in your area.

Alcohol and Octane

Alcohols like methyl alcohol (methanol) and ethyl alcohol (ethanol) are often used in race fuels. Sometimes they are a small part of the fuel and sometimes they are a primary component of the fuel. Methanol is commonly used “straight” – that’s why it’s called racing alcohol by many. Ethanol can also be used straight, and some racers do, but it’s more common to hear about E85, a blend of about 85% ethanol.

Much has been said about the octane rating of alcohols. However, technically speaking, the octane ratings of alcohols can not be measured.

All octane test engines, as defined in the octane rating procedures set forth by the American Society for Testing and Materials (ASTM), are carbureted. Air/fuel ratio adjustments on octane engine carburetors are limited and can not accommodate the extremely different air/fuel ratio requirements of pure alcohols.

Blends of alcohols can be tested to determine what is called a “Blending Octane Value” or BOV. Basically, the octane rating of an alcohol/gasoline blend is compared to the octane rating of the gasoline without alcohol and some math is done to calculate what the effect of the alcohol was on the octane of the gasoline. Thus, a BOV is determined. However, a BOV is not the same thing as a normal octane rating.

Octane numbers at the pump are determined by taking the average of two ASTM-specified octane tests – the Research Octane Number test (RON, or simply “R”) and the Motor Octane Number test (MON, or simply “M”). The average is expressed as (R+M)/2 and is sometimes referred to as the Antiknock Index or AKI. In the United States, pump gas is sold based on AKI and it is this value that we typically use to represent a fuel’s octane rating. The square yellow octane stickers you see on gasoline dispensers indicate the (R+M)/2 octane rating.

BOVs for methanol and ethanol typically overstate octane. This is because the law of diminishing returns applies. While a little alcohol can bump octane by a few numbers, twice as much alcohol does not result in twice as much octane increase. So while it may look like an alcohol has a high octane number when a small amount is used (as in determining a BOV), its real octane value is not as high. Problem is, the real number can’t be determined. so we’re left to guessing.

Ethanol is a good example. Its BOV is generally stated as 112 octane or so. Again, this implies that if you mix a little ethanol into gasoline, some math tells us the octane will increase as if the ethanol were 112 octane. In fact it’s not. it just seems that way when a small amount is added.

Best estimates of the actual octane rating of pure ethanol place it at about 100 octane. This is probably a conservative value but it is one we are comfortable with. If you see octane claims for ethanol in the 112 range, be suspicious that the octane number might be incorrectly based on BOV.

Ethanol

Ethanol is a renewable, domestically produced alcohol fuel made from plant material, such as corn, sugar cane, or grasses. Using ethanol can reduce oil dependence and greenhouse gas (GHG) emissions. Ethanol fuel use in the U.S. has increased dramatically from about 1.7 billion gallons in 2001 to about 12.6 billion in 2020. 1

E10 and E15

E10 and E15 are blends of ethanol and gasoline. The number after the «E» indicates the percentage of ethanol by volume.

Most of the gasoline sold in the U.S. contains up to 10% ethanol—the amount varies by region. All automakers approve blends up to E10 in their gasoline vehicles.

As of 2011, EPA began allowing the use of E15 in model year 2001 and newer gasoline vehicles. 2 Pumps dispensing E15 must be labeled (see example). A vehicle’s owner manual may indicate the maximum ethanol content recommended for it by the automaker.

Ethanol contains about one-third less energy than gasoline. So, vehicles will typically go 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on 100% gasoline. 3

E85 (Flex Fuel)

E85, also called flex fuel, is an ethanol-gasoline blend containing 51% to 83% ethanol, depending on geography and season. Summer blends tend to have more ethanol while winter blends have less. 4 E85 can be used in FFVs, which are specially designed to run on gasoline, E85, or any mixture of the two. FFVs are offered by several automakers. We provide a brief guide to help you determine if your vehicle can run on flex fuel.

MPG. Due to ethanol’s lower energy content, FFVs operating on E85 get roughly 15% to 27% fewer miles per gallon than when operating on regular gasoline, depending on the ethanol content. Regular gasoline typically contains about 10% ethanol. 5

Cost. The cost of E85 relative to gasoline or E10 can vary due to location and fluctuations in energy markets. E85 is typically cheaper per gallon than gasoline but slightly more expensive per mile.

Performance. Drivers should notice no performance loss when using E85. In fact, some FFVs perform better—have more torque and horsepower—running on E85 than on regular gasoline. 6,7,8

Availability. More than 3,900 filling stations in the U.S. sell E85. Visit the Alternative Fueling Station Locator for service station locations.

Domestically produced (reduces oil dependence)
Lower emissions of some air pollutants
More resistant to engine knock
Added vehicle cost is negligible

Can only be used in flex-fuel vehicles
Lower energy content (lower gas mileage)
Limited availability

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