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E85 vs Regular Gas: Mileage, Performance and Cost per Mile

Short answer: Expect fewer miles per gallon. fueleconomy.gov says flex-fuel vehicles typically get 15% to 27% fewer miles per gallon on E85 than on regular gasoline, with no loss in performance. E85 only saves money when its price per gallon is lower by more than your mileage drop.

How much mileage you lose

fueleconomy.gov puts the typical drop at 15% to 27% fewer miles per gallon on E85. The low end, 15%, is the difference in energy content between a 51% ethanol blend and E10. The high end, 27%, comes from EPA tests of recent flex-fuel models.

Why a range? E85 is not always 85% ethanol. The Alternative Fuels Data Center says it contains 51% to 83% ethanol, depending on where you are and the season.

Performance

fueleconomy.gov says flex-fuel vehicles see no loss in performance on E85, and some get more torque and horsepower than on gasoline. The Alternative Fuels Data Center adds that, other than lower fuel economy, drivers of flex-fuel vehicles see little difference.

Working out cost per mile

This is plain arithmetic, not a price quote. We do not list fuel prices, because we have no free, permitted source for them. Check the price at the pump.

Cost per mile is the price per gallon divided by your miles per gallon. If you get 20% fewer miles per gallon on E85, E85 has to cost at least 20% less per gallon than gasoline just to break even.

  • Example: your car gets 25 mpg on gasoline. At $3.00 a gallon that is 12 cents a mile.
  • On E85 it gets 20 mpg (20% fewer). E85 would need to cost $2.40 a gallon or less to match 12 cents a mile.
  • At $2.60 a gallon, E85 would cost 13 cents a mile, more than gasoline.

Last checked Oct 29, 2026.

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