Compare E85 flex fuel vs regular gasoline cost per mile. Account for E85's lower MPG to find the true cheaper option.
E85 (85% ethanol, 15% gasoline) is often priced lower than regular gasoline at the pump. However, E85 contains about 27% less energy per gallon, which means your vehicle gets significantly fewer miles per gallon when running E85. The real question is whether the lower pump price compensates for the reduced fuel economy.
This calculator compares the cost per mile of E85 versus regular gasoline by factoring in both the fuel price and the MPG difference. For flex-fuel vehicles that can run either fuel, this tells you which option actually saves money.
Typically, E85 needs to be priced at least 20–30% below regular gas to break even. In some states with ethanol subsidies, E85 is cheap enough to save money; in others, regular gas wins on a per-mile basis.
Whether you drive a compact sedan, a full-size SUV, or a pickup truck, accurate e85 vs regular gas figures help you plan smarter and avoid costly surprises at the pump or dealership. Use this tool regularly to track changes over time and adjust your transportation budget accordingly.
Pump price alone is misleading for E85. Because E85 delivers fewer miles per gallon, you need to compare cost per mile, not cost per gallon. This calculator does that comparison accurately so flex-fuel vehicle owners can make the right fueling choice. Results update instantly as you adjust inputs, making it easy to explore different scenarios and find the best option for your driving needs and budget.
E85 MPG = Regular MPG × MPG Reduction Factor (typically 0.73–0.80) Cost Per Mile = Fuel Price ÷ MPG Savings = Cost/Mile(Regular) − Cost/Mile(E85)
Result: Regular gas is cheaper by $0.013/mile
E85 MPG = 28 × 0.75 = 21.0. E85 cost/mile = $2.89/21.0 = $0.138. Regular cost/mile = $3.49/28 = $0.125. Regular saves $0.013/mile or about $195/year over 15,000 miles.
E85 contains about 73–83% of the energy in a gallon of regular gasoline. This is because ethanol has an energy density of 76,330 BTU/gallon versus 114,000 BTU/gallon for gasoline. The blended E85 result is approximately 83,000 BTU/gallon.
E85 pricing varies dramatically. In Iowa, Kansas, and Minnesota, E85 can be $0.60–$1.00/gallon cheaper than regular gas, often making it cost-effective. In California, New York, and Florida, the discount is typically $0.30–$0.50, which rarely beats regular on a per-mile basis.
E85 has an octane rating of 100–105, much higher than regular gas (87) or premium (93). Performance-modified vehicles can take advantage of this higher octane for more aggressive ignition timing and boost, potentially improving power output significantly.
Flex-fuel vehicle owners have the unique advantage of choosing their fuel based on current prices. Check E85 prices before each fill-up and choose the cheaper option on a per-mile basis. This flexibility can save $200–$400 per year in fuel costs in the right market.
Most flex-fuel vehicles lose 20–27% of their gasoline MPG when running E85. A car rated 28 MPG on regular gas will typically get 20–22 MPG on E85. The exact loss depends on the engine's ability to adapt its timing and fueling.
In flex-fuel vehicles, E85 is perfectly safe — they're designed for it with compatible fuel lines, seals, and engine management. In non-flex-fuel cars, E85 can damage fuel system components and should never be used.
E85 saves money when its pump price is more than 25–30% below regular gas. For example, if regular is $3.50, E85 must be below about $2.45–$2.63 to be the cheaper choice on a per-mile basis. This happens mainly in Midwest corn belt states.
Ethanol is a renewable fuel, and lifecycle CO₂ analysis shows E85 produces about 15–25% less greenhouse gases than gasoline. However, this depends on corn farming practices and varies by study. The per-mile emissions are higher due to lower MPG.
In flex-fuel vehicles, yes. The engine management system adjusts automatically to any blend. Mixing gives you intermediate performance and MPG. Many drivers fill half E85 and half regular for a balanced approach.
E85 prices are lowest in the Midwest where corn is abundant and ethanol plants are nearby. Federal and state ethanol subsidies and mandates also reduce costs. Coastal and southern states have higher E85 prices due to transportation costs.