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How to Know Whether Ethanol or Gasoline Is More Cost-Effective
The standard baseline benchmark is the 70% rule: if ethanol's price per unit is 70% or less than gasoline, ethanol generally gives you more driving distance per dollar.
For vehicles with non-standard engine efficiency ratios, switching to Advanced Mode computes your actual cost per mile or kilometer using your car's real mileage records.
Frequently Asked Questions
Why is the threshold 70% instead of 50%?
Because ethanol has lower volumetric energy density than gasoline. In flex-fuel internal combustion engines, ethanol yields approximately 30% less mileage per gallon or liter. That puts the break-even point near 70%.
Is advanced mode more accurate than the 70% rule?
Yes. The 70% threshold is a general heuristic. Real vehicle models and individual driving styles vary. Providing actual fuel economy guarantees accurate math.
Do I have to pay or create an account to use this?
No. This web tool is 100% free with no login required.
Is my data uploaded to a server?
No. Calculations run client-side right in your browser.