Methodology

How the numbers are made

DriveCostCheck estimates driving energy cost — the fuel and/or electricity a vehicle consumes — and nothing else. It is not a total-cost-of-ownership calculator: depreciation, maintenance, insurance, financing, taxes, and repairs are out of scope because no reviewed source backs them here.

Inputs

One exact EPA vehicle record. Every calculation starts from a single FuelEconomy.gov configuration (year, make, model, engine, transmission, drivetrain). Trims with different efficiency values are never merged.
Annual mileage. Default 12,000 miles/year, always visible and editable (a monthly input is provided too). This is deliberately not the 15,000-mile assumption used by the EPA's official annual fuel cost estimate — when you see the official figure on this site it is labeled with its own assumption.
Driving mix. Share of miles in city vs highway conditions. Default 55% city / 45% highway — the same weighting the EPA uses for combined ratings — with presets and a slider.
Energy prices.Fuel defaults are the official FuelEconomy.gov national averages, shown with their retrieval date. Electricity is the one exception: it comes from EIA's U.S. Total residential price, the same table every per-state electricity figure on this site is drawn from, so the national default and the state defaults share a source. Every price can be overridden; overridden values are visibly marked Custom.

Gasoline and diesel vehicles (including conventional hybrids)

Fuel is computed per driving segment from consumption, then priced. MPG values are never arithmetically averaged — averaging MPG understates fuel use because MPG is a distance-per-volume ratio:

city gallons = (annual miles × city share) ÷ city MPG highway gallons = (annual miles × highway share) ÷ highway MPG annual cost = (city gallons + highway gallons) × price per gallon

When a record lacks separate city/highway values, the EPA combined value is used as a clearly labeled fallback and the driving-mix control has no effect. The gasoline grade (regular, midgrade, premium) follows the record's official fuel type. Natural-gas vehicles use gasoline-gallon equivalents (GGE) priced at the official per-GGE average.

Battery-electric vehicles

city kWh = (annual miles × city share) × city kWh/100mi ÷ 100 highway kWh = (annual miles × highway share) × highway kWh/100mi ÷ 100 annual cost = (city kWh + highway kWh) × price per kWh

EPA electricity-consumption values are measured from the wall outlet, so typical home AC charging losses are already included in the official figures. Public DC fast-charging prices, extreme temperatures, and driving style can still change real-world cost — the result is an estimate under the stated assumptions. For a few records that lack kWh/100mi fields, consumption is derived from the MPGe label value (33.705 kWh per gallon-equivalent) and the page says so explicitly.

Plug-in hybrids

PHEV labels mix two energy sources, and the composite MPGe shown on the window sticker cannot be used as ordinary MPG. DriveCostCheck never does. Instead, the calculation splits miles into an electric (charge-depleting) share and a gasoline (charge-sustaining) share:

electric miles = annual miles × electric share gas miles = annual miles − electric miles electric cost = electric miles × EPA charge-depleting kWh/100mi ÷ 100 × price per kWh CD gasoline = electric miles × EPA charge-depleting gal/100mi ÷ 100 (blended PHEVs) CS gasoline = weighted-consumption gallons over gas miles (formula above) annual cost = electric cost + (CD gasoline + CS gasoline) × price per gallon

The electric share defaults to the record's official EPA utility factor — the modeled fraction of miles a typical driver covers in charge-depleting mode when charging once per day — and the page asks you to adjust it to match your charging habits. If a record has no utility factor, the default is 50% with an explicit note. If a PHEV record lacks the fields for this split entirely, DriveCostCheck shows only the official FuelEconomy.gov estimate and says a custom result is not supported for that record.

Hydrogen fuel-cell vehicles

Hydrogen MPGe treats one kilogram of H₂ as one gasoline-gallon equivalent, so kilograms = miles ÷ MPGe. FuelEconomy.gov publishes no national hydrogen price, so a cost appears only after you enter your local price per kilogram.

Displayed figures and rounding

All arithmetic uses exact values; rounding happens once, at display time.
Annual costs display as whole dollars; monthly as dollars and cents.
The five-year figure is exactly 5 × the displayed annual figure, so the arithmetic you can check never contradicts itself. Five-year totals assume today's prices for all five years — energy prices will change.
Cost per mile displays in cents at one decimal.
Monthly and annual figures are rounded from the same underlying calculation; monthly × 12 can differ from the annual figure by a few cents of rounding, never more than six.

What the estimates are not

EPA figures are standardized laboratory estimates designed for comparison between vehicles. Your real-world consumption varies with temperature, terrain, load, maintenance, and driving style. DriveCostCheck shows the assumptions next to every result so you can change them, and links each vehicle to its official record. See Data & sources for snapshot dates and checksums, and Corrections if a number looks wrong.