How we use the data

Sources

Complaints, recalls and crash ratings come from the National Highway Traffic Safety Administration (NHTSA). Fuel economy comes from the U.S. Environmental Protection Agency (EPA) at fueleconomy.gov. All of it is U.S. government public-domain data. Complaint and recall data on this site runs through July 26, 2203.

What a complaint is

A complaint is a report an owner filed with NHTSA. NHTSA does not verify it. We quote complaint text as filed, shortened, with phone numbers, email addresses, links and VINs removed and all-capital text converted to normal case.

Complaint counts and sales

We do not have sales figures for each model year, so complaint counts are not adjusted for how many cars were sold. A best-seller will collect more complaints than a rare car with the same problem rate. That is why we call the lists "most complaints", never "least reliable", and why best and worst year pages use the comparison described below.

The five-year window

Older model years have had more time to collect complaints. To compare years fairly, the best and worst years pages count only complaints about failures that happened within five years of the model year, and only for model years whose five years are complete. More recent years are shown separately and marked as too recent to compare.

Mileage

Many complaints include the odometer reading when the problem appeared. We use readings between 1 and 400,000 miles and report the median: half of those complaints happened before that mileage. Complaints without a usable reading are left out of mileage figures only.

Severity

Each complaint gets a severity score: 1 point, plus 3 if it mentions a crash, 5 for a fire, 4 for any injury (and 1 more per injured person, up to 5), and 10 for any death (and 2 more per death, up to 5). We use the score to choose which complaints to quote first and to say when a model year's complaints are more or less severe than most.

Matching NHTSA and EPA names

The two agencies name the same car differently, for example "F150" and "F-150 Pickup 2WD". We normalize names, match on model and trim words, and keep a hand-maintained list of exceptions. Each match has a confidence score. Fuel economy is shown on a page only when the match confidence is at least 90%; lower-confidence matches are left out rather than risk showing another car's numbers.

When a page exists

A model year gets a problems page when it has at least 25 complaints, and a part page when that part has at least 15. Comparison pages cover only the most-complained-about models of the same type and model year. Rankings state exactly what they measure. We would rather have no page than a thin one.

Corrections

If you see an error or a mismatch between a car and its data, please contact us.