Two real numbers multiplied, not a national average

Every page on this site multiplies two genuinely sourced figures: EIA Electric Power Monthly, Table 5.6.B, residential, by state (src/data/rates-by-state.csv), and EPA/DOE fueleconomy.gov bulk vehicles.csv, combined kWh/100mi (src/data/ev-models.csv). Lucid Air Pure RWD with 19 inch wheels at 23.141 kWh/100mi and Vinfast VF 8 Plus at 76.0938 kWh/100mi show how wide that spread actually is — more than 3x — which is why one national EV efficiency number would hide more than it reveals.

The gas-car comparison, and what it isn't

EIA Weekly Retail Gasoline Prices, regular grade, all formulations, US average, week of 2026-08-24. EPA Automotive Trends Report, model year 2024 — gasoline-only new-vehicle fleet average (27.2 mpg blended minus the reported 1.7 mpg BEV/PHEV lift). Both are national constants, not per-state figures — EIA does not publish a state-level retail gasoline price series, only regional (PADD) ones, so this site is honest about using one national number for the gas side rather than manufacturing a false per-state precision it can't back up.

Why charger losses aren't double-counted

EPA's kWh/100mi figure is measured "from the wall" — a calibrated AC energy meter sits between the outlet and the vehicle during the dynamometer test, so charger and onboard-converter losses are already folded into the published number. Applying a separate home-charging-loss factor on top would overstate the true cost, so this model applies none.

Annual mileage and full-charge cost

fueleconomy.gov's own fuel-cost-calculator default annual-mileage assumption: 15,000 miles/year. The full-charge figure on each page is the EPA's own combined range multiplied by the EPA's own consumption rate — the energy actually used in the EPA test, not the battery pack's nameplate capacity, which isn't in this dataset.