Where our numbers come from

Mileage and fuel cost

U.S. Environmental Protection Agency and U.S. Department of Energy, fueleconomy.gov, the vehicle data file vehicles.csv (50,647 tested versions of cars sold in the U.S.). File dated 2026-11-04.

• City, highway and combined figures are copied as they are in the file.
• The agency's yearly fuel cost assumes 15,000 miles a year. The agency's yearly cost is printed as the agency's own figure. The calculators do not use it as a price: each one starts at the dated price of the fuel the version burns (see Fuel prices below).
• For electric and fuel-cell cars the file gives MPGe, miles per gallon of gasoline energy. One gallon of gasoline holds as much energy as 33.705 kWh, which is the agency's own conversion; the calculator uses it to work in kWh.
• A model is a "base model" of the file (the model name without trim) in one model year; its versions are every tested engine, gearbox and drive combination.

Emissions and class rank

Tailpipe CO2 in grams per mile, the fuel economy score and the greenhouse gas score (1 to 10, 10 is best) are columns of the same EPA file. A minus-one marker or an empty cell means the agency gave no figure and the page leaves it out. The class rank compares the best version of every model of one EPA class and model year in the whole file; ties share the better place; electric and fuel-cell cars are ranked apart, in MPGe. The mileage rank uses the best version of each model. The fuel-cost rank and the CO2 rank use each model's lowest figure over its versions, so a model is not ranked on a version that is not its cheapest; versions with no fuel-cost figure (fuel-cell and plug-in hybrid versions, see below) are left out of the cost rank.

Five-year fuel cost

The five-year figure on the car pages and the compare page is 5 times the yearly figure worked out from the miles and the prices shown, so the yearly and the five-year sentences always agree. The file's own "you save or spend over 5 years compared with the average new car" column is not used for any sentence.

Hydrogen cars and plug-in hybrids

The EPA file gives no fuel-cost estimate for hydrogen cars and no dollar price for hydrogen, so no yearly cost, cost per mile, five-year cost or dollar comparison is shown for them; the calculator works only when you type a price per kilogram. For plug-in hybrids the file's yearly cost is for driving on gasoline alone, and the electric cost column of the file is empty. The page shows the gasoline-only figure with that label and the electric figures (kWh per 100 miles, MPGe, electric range); the real cost depends on how often the car is charged, so no blended cost is shown and these versions are left out of the fuel-cost ranks and the dollar comparisons. (A blended cost from the agency's utility factor was tried against the file's own five-year figures and did not reproduce them for all plug-in hybrids, so it is not used.)

Fuel prices

U.S. Department of Energy / EPA, fueleconomy.gov fuel prices, fetched once when the site is built; every page prints the date. Each version starts at the dated price of its own fuel (regular, midgrade or premium gasoline, diesel, E85, electricity), taken from its fuel type in the EPA file. In the rival box, the payback box and the compare page the price you type applies to the car or version it sits next to; another car or version keeps the dated price of its own fuel unless both burn the same fuel, and then one price drives both. Hydrogen has no published price, so its box starts empty. When no dated price was loaded, the calculator starts from the price behind the agency's yearly estimate and says so.

Crash-test ratings

U.S. National Highway Traffic Safety Administration, 5-Star Safety Ratings, by make, model and model year. Not every model is rated; a page says "not rated" only when the agency knows the model and its list came back empty, says "could not match" when the model is in none of the agency's lists under a fitting name, and says "not loaded" when the data was not fetched for that page. How names are matched is described under "Matching model names" below.

Owner complaints

U.S. National Highway Traffic Safety Administration, complaints by vehicle. A complaint is a report an owner sent to the agency; it is not a proven defect, and the counts are not adjusted for sales. The site keeps only counts (total, the parts named, and how many reports mention a crash, a fire or an injury). It does not copy or show any owner's text. The agency's service answers with an empty list both for a model without complaints and for a name it does not know, so an empty answer alone says nothing; the page tells the two apart with the name match described under "Matching model names" below.

Safety recalls

U.S. National Highway Traffic Safety Administration, recalls by make, model and model year. Each page shows the date it was checked. A page that says recall data was not loaded has no recall figure at all; it does not mean the car has no recalls. The agency's service gives the same empty answer for a model without recalls and for a name it does not know, so the page says "the database returned no recalls" only when the agency's model list has the model, and says "could not match" otherwise.

Matching model names

The EPA file and the safety agency do not always name a model the same way: the EPA says "Civic", the agency says "CIVIC SEDAN" and "CIVIC HATCHBACK"; the EPA says "F150", the agency "F-150". When the site is built, the agency's own model lists are fetched for every brand and model year (all models, models with recall records, models with complaint records, models with ratings). An agency name belongs to an EPA model when the two are the same after ignoring case, spaces and hyphens, or when the agency name starts with the EPA name followed by a space ("CAMRY HYBRID" belongs to Camry). When two EPA models fit, the longer EPA name wins, so "BRONCO SPORT" goes to the Bronco Sport and not to the Bronco. Recalls, complaints and ratings are asked for under every matching name and merged; recalls are counted once per campaign number and complaints once per report number. Each car page then says one of four things: the figures; that the agency's list has the model and returned nothing; that the model could not be matched to the agency's list (a naming gap, not a clean record); or that the data was not loaded. At most six names are asked for one car. When records were merged from more than one agency name, the page prints those names as the agency spells them. A heavy-duty name (a number of 2500 or more, or "HD", such as "SILVERADO 2500 HD") is a vehicle line the EPA versions on the page do not cover: for those cars the names are asked one by one and saved per name, only the names that fit the EPA versions (the plain name, "1500", and an EV name where the page has an electric version) are counted on the page, and the page says which heavy-duty names were left out. A plain name or a "1500" name is the same line as the EPA's own model. The page also says so when a name carries an electric or hybrid word that the EPA versions on the page do not have.

Compare page and statistics

The compare page and the statistics page use the same files and the same arithmetic as the car pages. The statistics page names the method and the number of samples behind every finding and leaves out a finding with fewer than 10 samples; its recall and complaint counts cover only the cars whose agency data was loaded.

How often it is updated

The pages are built again when the agencies publish new files. The dates on each page show the data used. This build was made on 2026-11-14; the EPA file is dated 2026-11-04.

What we do not do

We do not test cars, we do not guess missing figures, and we do not publish a figure that is not in these files. We do not cover purchase price, towing capacity, reliability or repair costs. If you find a mismatch, tell us on the contact page.