Methods and data

Every figure on this site comes from one public file. This page says which file, what was done to it, what each number means and where the limits are.

Where the data comes from

The ratings are the vehicle fuel economy data published by the US Environmental Protection Agency (EPA) and the US Department of Energy (DOE) on fueleconomy.gov. The file used is vehicles.csv.zip, retrieved on 2026-10-13. Its checksum starts with 33d32caa0343cdb1, so a later change to the source can be told apart from a change in this site. The file holds 50,407 records covering model years back to 1984.

Licence and terms: No separate licence or usage terms are stated on the fueleconomy.gov download or web services pages (read 2026-10-13). The data are produced for the US Department of Energy and the US Environmental Protection Agency: fueleconomy.gov states that the fuel economy data are the result of vehicle testing done at EPA's National Vehicle and Fuel Emissions Laboratory and by vehicle manufacturers with oversight by EPA, and that the website is administered by Oak Ridge National Laboratory for the U.S. Department of Energy and the U.S. Environmental Protection Agency. They are works of the US federal government, which are not subject to copyright in the United States (17 U.S.C. 105), so they may be reused and republished; this site credits the source on every page that uses it.

What was kept and what was dropped

The site keeps model years 2019 to 2026. Model year 2027 is already in the file but is only partly published (539 records against 1,172 for 2026), so ranking it would compare an unfinished list with a complete one.

1. model years 2019 to 2026: 10,264
2. usable rating, cost and fuel price: 10,229
3. exact duplicates removed: 10,227
4. models (make + base model + powertrain): 713
5. models with ratings in the current model year: 368

Records dropped as unusable:

• hydrogen fuel cell: 35

A model is a make plus EPA's base model name. When the same base model is sold with several powertrains (a gasoline Camry and a hybrid Camry), each powertrain is its own model so that a hybrid is never ranked as if it were the gasoline car. Its headline figure is the most efficient rated version in the newest year the model appears; all versions are listed on its page. 368 of the 713 models were rated for model year 2026; the rest have a page showing their last rated year but are left out of the current rankings.

What the numbers mean

• Combined MPG is EPA's combined city and highway estimate in miles per US gallon. For electric models the file gives MPGe: the miles driven on 33.7 kilowatt-hours of electricity, the energy in a gallon of gasoline. For plug-in hybrids the figure is for running on fuel with the battery depleted.
• Annual fuel cost is the file's own figure. It assumes 15,000 miles a year, 55% city and 45% highway driving and the fuel prices below. The same prices are applied to every model year, so costs of older models are what they would cost to fuel today.
• Tailpipe CO2 is grams per mile at the tailpipe. It is zero for electric models and does not include the emissions of making the electricity or the fuel.

The default prices are the ones fueleconomy.gov's own fuel price service listed on 2026-10-13. The last column divides each model's annual cost in the file by the gallons its ratings imply and takes the median of the 2026 models; the two agree to within a few cents, which is how the build checks that the cost figures follow from the ratings. Where you type your own mileage or prices, costs are scaled in proportion; nothing else on the page changes.

How rankings, ranks and medians are worked out

A rank is one plus the number of models in the same group that are strictly better on the measure, so models with identical ratings share a rank. "Ahead of X% of them" is the share of the other models in the group that this one beats outright, rounded to a whole percent. A median is the middle value of the group, or the mean of the two middle values. These statistics are only shown for groups of at least five models. The self-test of every build recomputes them with a second, independent method and fails if the two disagree.

64 ranking pages are built: one for each of the 12 EPA size classes, one for each powertrain, one for each make with at least four models in the current year, and a class-and-powertrain page when it is a real subset of its class rather than nearly the whole of it.

How comparison pairs are chosen

Within each EPA vehicle class and powertrain, the twenty models rated in the most model years of the data (a stand-in for long-running nameplates; the file has no sales figures) are paired with each other when they come from different makes, longest-running pairs first. Each model appears in one pair only, so no two comparison pages are about the same car, and models whose ratings are almost identical to another model's are not paired. This gave 107 pairs. The file has no sales figures, so the choice says nothing about which cars sell most, and a pair being listed is not a recommendation.

Limits

• EPA ratings are laboratory-based estimates for comparing models, not predictions for your car. Driving style, weather, load and maintenance change real mileage.
• The file has no prices, reliability, safety or comfort data, so this site does not say which vehicle is better to own and gives no buying advice.
• The headline figure of a model is its most efficient version. Other versions of the same model can be considerably less efficient; the version table on each page shows them.
• EPA revises estimates from time to time. Figures here are those in the file retrieved on the date above.

Spotted something wrong? Tell us through the contact page and we will check it against the source file.