- E85 contains 15–27% less energy per gallon than regular gasoline, directly reducing fuel economy by a comparable amount.
- E85 is typically 20–25% cheaper per gallon than regular, but the per-gallon savings rarely offsets the MPG penalty.
- On a cost-per-mile basis, E85 is usually more expensive than regular gasoline unless the per-gallon discount exceeds about 25%.
- Only flex-fuel vehicles (FFVs) can safely use E85. Using E85 in a non-FFV vehicle can cause engine damage.
01 What Is E85
On a cost-per-mile basis, E85 is usually more expensive than regular gasoline despite costing 20–25% less per gallon, because it also contains 15–27% less energy per gallon. E85 is a fuel blend containing 51–83% ethanol and the remainder gasoline. The “85” refers to the maximum ethanol percentage, though the actual blend varies seasonally: lower ethanol content in winter to aid cold starting, and higher in summer. The DOE’s Alternative Fuels Data Center classifies E85 as an alternative fuel distinct from standard gasoline blends like E10 (10% ethanol) and E15 (15% ethanol).
DOE, Alternative Fuels Data Center (AFDC), "Ethanol Fuel Basics"; EPA, "E85 and Flex Fuel Vehicles"E85 can only be used in flex-fuel vehicles (FFVs), which have fuel systems designed to handle ethanol’s corrosive properties and different combustion characteristics. FFVs can run on any blend from pure gasoline to E85. According to DOE data, there are approximately 21 million FFVs on U.S. roads, though many owners are unaware their vehicle is flex-fuel capable.
DOE, Alternative Fuels Data Center, "Flexible Fuel Vehicles"; EPA, Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends ReportE85 availability has grown substantially over time. The number of public and private E85 stations in the U.S. grew from 113 in 2000 to 3,946 in 2020 and 5,100 in 2025, a more than 45-fold increase over 25 years, though E85 stations remain a small share of the overall fueling network.
DOE, Alternative Fuels Data Center, U.S. Public and Private Alternative Fueling Stations by Fuel Type, 1992–202502 Energy Content Difference
The fundamental challenge with E85 is its lower energy density. Ethanol contains approximately 76,330 BTU per gallon compared to 114,000 BTU per gallon for gasoline, about 33% less energy. Since E85 is a blend, its energy content falls between pure ethanol and pure gasoline.
DOE, Alternative Fuels Data Center, "Fuel Properties Comparison"; ORNL, Transportation Energy Data Book, fuel energy content tables| Fuel | Energy (BTU/gal) | % vs Gasoline |
|---|---|---|
| Regular gasoline (E10) | 114,000 | 100% |
| E85 (summer, ~83% ethanol) | ~83,000 | 73% |
| E85 (winter, ~51% ethanol) | ~97,000 | 85% |
| Pure ethanol (E100) | 76,330 | 67% |
This means a vehicle running on summer E85 needs roughly 27% more fuel by volume to travel the same distance as on regular gasoline. In winter E85, the penalty is about 15%. The DOE reports that real-world fuel economy reductions range from 15% to 27% depending on the seasonal blend.
DOE/EPA, fueleconomy.gov, "Flexible Fuel Vehicles": "FFVs operating on E85 typically get 15% to 27% fewer miles per gallon than when operating on regular gasoline"03 Price Comparison
The DOE tracks E85 and gasoline retail prices at stations across the country through its Clean Cities Alternative Fuel Price Report. E85 is typically priced 20–25% below regular gasoline on a per-gallon basis, though the discount varies by quarter and by station.
DOE, Alternative Fuels Data Center, Clean Cities Alternative Fuel Price Report (quarterly, national average)| Period | Regular ($/gal) | E85 ($/gal) | E85 Discount |
|---|---|---|---|
| Q1 2024 | $3.23 | $2.49 | −23% |
| Q2 2024 | $3.56 | $2.67 | −25% |
| Q3 2024 | $3.36 | $2.62 | −22% |
| Q4 2024 | $3.07 | $2.39 | −22% |
| Q1 2025 | $3.10 | $2.39 | −23% |
| Q2 2025 | $3.16 | $2.53 | −20% |
| Q3 2025 | $3.14 | $2.48 | −21% |
| Q4 2025 | $2.99 | $2.30 | −23% |
The DOE's national price survey does not break results out by state, so state-by-state E85 discount claims can't be verified from this data. Anecdotally, Midwest states near ethanol production facilities tend to see larger discounts, but that pattern isn't quantified in the national report used here.
For the longer view on regular gasoline pricing behind these quarterly figures, see gas prices by year, 1950 to 2025.
04 Cost per Mile Analysis
The per-gallon price advantage of E85 is misleading without accounting for the fuel economy penalty. The true comparison requires calculating cost per mile for each fuel. The table below shows a representative flex-fuel vehicle (rated 24 MPG on gasoline, 18 MPG on E85) at various price points.
DOE/EPA, fueleconomy.gov; representative FFV fuel economy ratings from EPA database| Scenario | Regular $/mi | E85 $/mi | E85 Savings |
|---|---|---|---|
| Regular $3.50, E85 $2.80 (−20%) | $0.146 | $0.156 | −$0.010 (costs more) |
| Regular $3.50, E85 $2.63 (−25%) | $0.146 | $0.146 | Break-even |
| Regular $3.50, E85 $2.45 (−30%) | $0.146 | $0.136 | +$0.010 (saves) |
| Regular $3.00, E85 $2.25 (−25%) | $0.125 | $0.125 | Break-even |
| Regular $4.00, E85 $3.00 (−25%) | $0.167 | $0.167 | Break-even |
Estimate your vehicle's driving cost using official EPA fuel economy data.
Use the Calculator05 When E85 Actually Saves Money
E85 becomes cost-effective in specific circumstances:
DOE, AFDC, "Flexible Fuel Vehicles: Cost of Driving"; EIA, regional fuel price data- States with larger-than-average discounts: Where local E85 pricing runs well above the ~20-25% national average discount (commonly reported in Midwest states near ethanol production), E85 can genuinely save money. The DOE's national price survey doesn't publish a verified state-by-state breakdown, so check local station prices directly.
- Winter blends with smaller MPG penalty: Winter E85 (51% ethanol) causes a smaller fuel economy drop (~15%), meaning a smaller per-gallon discount is needed to break even.
- High gasoline price environments: When gasoline prices spike above $4.00 per gallon, E85 discounts tend to widen in absolute dollar terms, sometimes reaching 30%+ below regular.
For an FFV driver covering 12,000 miles per year on a representative 24 MPG gasoline / 18 MPG E85 vehicle, using the 2024–2025 average national prices above ($3.20/gal regular, $2.48/gal E85), E85 actually costs about $53 more per year than regular: the roughly 23% average discount falls short of the 25% needed to break even on this vehicle. The DOE recommends that FFV owners compare the cost per mile at their local stations rather than relying on per-gallon prices alone.
Calculated: (12,000/18 × $2.48) − (12,000/24 × $3.20) = $1,653 − $1,600 = $53. Prices are 2024–2025 averages from the table above.For a vehicle getting 24 MPG on gasoline and 18 MPG on E85, and regular gas at $3.50/gallon: E85 must be $3.50 × (18/24) = $2.63 or less to save money. At current typical E85 prices, this threshold is not consistently met in most markets outside the Midwest.
Calculated using DOE break-even methodology; representative FFV fuel economy ratings06 Data Sources
- DOE: Alternative Fuels Data Center – "Ethanol Fuel Basics" and "Flexible Fuel Vehicles." afdc.energy.gov
- DOE: Clean Cities Alternative Fuel Price Report, quarterly national averages through Q4 2025. afdc.energy.gov
- DOE/EPA: FuelEconomy.gov – "Flexible Fuel Vehicles." fueleconomy.gov
- EIA: Weekly Retail Gasoline Prices. eia.gov
- DOE: Alternative Fuels Data Center, U.S. Public and Private Alternative Fueling Stations by Fuel Type, 1992–2025. afdc.energy.gov