Methodology & data sources
Transparency is the point of this site. This page documents exactly where every number comes from and how each derived figure is calculated, so you can reproduce or challenge it. Data as of June 2026.
Data sources
| Source | What we use it for | License |
|---|---|---|
| EPA / DOE FuelEconomy.gov | Per-vehicle combined MPG / MPGe, electricity use (kWh/100mi), EPA estimated annual fuel cost, all-electric range and tailpipe CO2 (2023–2027 model years). | U.S. public domain |
| EIA — gasoline prices | National-average gasoline price used as the default in the calculators and derived cost-per-mile figures. | U.S. public domain |
| EIA — electricity prices | National-average residential electricity price used for EV/PHEV energy cost. | U.S. public domain |
We snapshot the EPA dataset and commit it as static JSON; we do not call any API at request time. If a model has no real EPA figure, we omit it rather than estimate one. For each model we publish the latest EPA model year available and a representative mainstream trim (the median by annual fuel cost), so figures reflect a typical configuration, not an outlier performance or stripped-out trim.
Default prices & driving assumptions
- Gasoline: $3.40 per gallon (EIA US average, June 2026).
- Electricity: $0.18 per kWh (EIA US residential average, June 2026).
- Annual mileage: 15,000 miles/year (matches the EPA's basis).
- Ownership period: 5 years for all "5-year" figures.
You can override the prices and mileage in every calculator; the defaults are only a starting point.
Formulas (all derived figures)
- EPA annual fuel cost — shown unmodified, exactly as published by the EPA (window-sticker figure, 15,000 mi/yr at EPA reference prices).
- Annual fuel cost (gas/hybrid) = (miles ÷ MPG) × price per gallon.
- Annual energy cost (EV) = (miles ÷ 100) × kWh per 100 mi × price per kWh.
- Cost to drive 1,000 miles = the above evaluated at 1,000 miles and EIA prices.
- Cost per mile = cost to drive 1,000 miles ÷ 1,000.
- 5-year fuel cost = EPA annual fuel cost × 5.
- EV-vs-gas break-even (years) = (EV price − gas price) ÷ annual fuel saving.
- Rankings — cheapest to run sorts by EPA annual fuel cost; most fuel-efficient sorts gas/hybrid/PHEV by combined MPG; best EVs sorts EVs by MPGe (and separately by range). MPG and MPGe are never mixed in one ranking.
The 5-year cost-to-own estimate (important)
The cost-to-own total combines four lines. Only the first is EPA data:
- Fuel / energy = EPA annual fuel cost × 5 (real EPA data).
- Maintenance & repairs — a documented assumption by body type, reduced for hybrids/EVs (which need less servicing): base car ~$4,500, SUV ~$5,200, pickup ~$6,000 over 5 years, ×0.85 for hybrid/PHEV and ×0.6 for EV.
- Insurance — a documented assumption by body type (~$7,500 car, higher for SUV/pickup, +10% for EV) over 5 years.
- Depreciation — an illustrative assumption by body/powertrain (~$14,000 car, higher for SUV/pickup, ×1.25 for EV) over 5 years.
These three non-fuel lines are not model-specific data. They are transparent, typical-range placeholders so you can compare vehicles on a like-for-like basis and see the shape of total cost (depreciation usually dominates). Real depreciation, insurance and maintenance vary enormously by trim, location, driver, mileage and market. Use the cost-to-own calculator to replace them with your own quotes. We label these as estimates everywhere they appear.
How calculations run
All calculators run entirely in your browser using the formulas above. We do not store your inputs and the site sets no tracking cookies of its own.
Limitations
EPA ratings are standardized lab estimates; real-world MPG/MPGe and range vary with driving style, weather, terrain and conditions. Fuel and electricity prices are volatile national averages — your local price will differ. Cost-to-own figures are estimates for comparison, not quotes or financial advice. Always verify against the primary EPA source and get real quotes before making a purchase. See our disclaimer.