Frequently sold as Unleaded 88, E15 is a blend of 15% ethanol and 85% gasoline. It contains 5% more ethanol than E10, which is the most common fuel used in the U.S. E15 is higher in octane — typically 88 octane while E10 has an octane rating of 87. Retailers are offering E15 as Unleaded 88 to highlight its high octane value.
Until recently, gasoline ethanol blends were limited to a maximum of 10% ethanol known as E10. E10 represents 97% of the gasoline sold in the U.S. Unleaded 88 uses the same type of ethanol as blended in E10 but increases the ethanol content in a gallon of gasoline from 10% to 15%.
Unleaded 88 has been approved by the U.S. Environmental Protection Agency (EPA) for use in all 2001 and newer cars, trucks and SUVs. EPA estimates that over 90% of gasoline sold goes into model year 2001 and newer vehicles.
In 2009, the ethanol industry petitioned EPA to approve a blend up to 15% ethanol in gasoline, from the current cap of 10%. Raising the blend from E10 to E15 would accelerate the use of renewable fuel, increase energy security, create U.S. jobs, reduce transportation costs, and improve the environment by displacing conventional gasoline with low-carbon ethanol.
There has been more testing of Unleaded 88 than any other fuel additive in the history of the EPA fuel waiver process. In 6 million miles of testing, the U.S. Department of Energy found no problems with the use of Unleaded 88 in the numerous vehicles selected.
Auto manufacturers approve the use of Unleaded 88. According to an RFA analysis, more than 93% of model year 2019 vehicles have been explicitly approved for the use of Unleaded 88 by auto manufacturers. General Motors recommends use of Unleaded 88 beginning with its 2012 model year vehicles and Ford recommends Unleaded 88 for its 2013 and newer vehicles. Unleaded 88 is also approved for use by Volkswagen, Audi, Toyota, Land Rover, Porsche, Jaguar, Honda, Subaru, and certain models of Mercedes-Benz and Lexus.
It’s also important to note that specific fuels and fuel additives are not always referenced in vehicle owner’s manuals, such as fuel stabilizers or octane boosters. Use of fuels and fuel additives not mentioned does not necessarily void a vehicle warranty. In fact, vehicle manufacturers may not deny a warranty claim based on use of a different fuel if that fuel did not contribute to the problem for which the warranty claim is made.
In a real-world environment, the difference in mileage between Unleaded 88 and regular gasoline is virtually undetectable. Studies by Oak Ridge National Laboratory and the National Renewable Energy Laboratory have shown that with all other things being equal, in a controlled environment, ethanol’s impact on fuel economy would be equal to the loss of energy density. This translates into a loss of less than 2% for Unleaded 88 when compared to regular gasoline. For a vehicle getting 30 mpg this would equate to a drop to around 29.4 mpg, or about the loss of miles to the gallon when vehicle tires are improperly inflated.
A U.S. Department of Agriculture analysis shows that ethanol continues to significantly reduce greenhouse gases (GHG). The study notes that ethanol use in transportation fuel reduces GHG by 43% and projects that, based on current trends, these reductions will reach 47% by 2022.
Unleaded 88 can easily be identified at the pump. Look for the government-required orange and black label referencing E15 for use in 2001 and newer passenger vehicles and flex-fuel vehicles (as seen on the right).
Unleaded 88 can be used in nearly all existing fuel infrastructure without risk of damage. Underwriters Laboratories announced its research supports the use of fuel blends containing 15% ethanol at America’s gas station pumps.
EPA did not approve the use of Unleaded 88 in 2000 and older model vehicles. This was primarily due to the fact that these older vehicles have a number of variables – mileage, state of repair, types of use – that would result in inconclusive test data.
Non-automotive uses for Unleaded 88 were not approved by EPA because many non-automotive engines do not have the sophisticated computer controls to adjust for fuel variations. These engines have numerous applications and vary in types and sizes.