Why Does MPG Drop on E85?
Ethanol is an alcohol-based fuel that carries less energy per gallon than gasoline. According to the Alternative Fuels Data Center, while it has a much higher octane rating (allowing for more horsepower and timing advance), it requires more volume to produce the same amount of thermal energy.
- Gasoline (E10): ~114,000 BTU/gallon
- E85 (85% Ethanol): ~81,800 BTU/gallon
This difference typically results in a 25% to 30% reduction in fuel economy when running fully on E85. However, the cost savings at the pump often outweigh the MPG loss. Check our Cost Calculator to see if E85 makes financial sense for you.