How the numbers are made
Sources
Three NHTSA files, read daily: the consumer complaint file (every complaint received since 2015 is in the current chunks), the recalls database by make, model and year, and the defect investigation file. All three are public and free. Nothing on this site comes from forums, social media, warranty claims or repair shops.
Counting
One complaint is one count, even when NHTSA lists it under several components. A complaint that names both the engine and the electrical system appears in both systems' totals but once in the vehicle total.
Problem groups
Each problem on a vehicle page is a group of complaints that share a NHTSA component and mention a set of words. Sticky steering, for instance, is every steering complaint that says stick, notch, jerk, bind or catch. The groups are the same for every vehicle, so they miss problems unique to one model and they sometimes catch a report that belongs elsewhere. A report can sit in more than one group. A group needs 25 reports before it gets its own page and 8 reports with a mileage before it gets a bar on the mileage track.
Mileage
About a third of complaints state the mileage at failure in NHTSA's field for it. Where the owner wrote the mileage in the text instead, the site reads it from there. The bar for a problem covers the middle half of those mileages, from the 25th to the 75th percentile, with a tick at the median. Vehicles with fewer than 40 complaints don't get a page.
Prices
Dollar figures come only from complaints that quote one, between $100 and $15,000. Owners quote what they were charged, what they were quoted, and sometimes what the car cost, so read the strip as a spread of what people mentioned rather than a repair estimate.
Tick sheets
The phrases on a symptom sheet are word patterns. Ticking several counts only the reports that contain all of them. The count is a way to see whether your combination of symptoms is common on this car, not a diagnosis.
First-year pages
A model year from 2025 on gets a log instead of a mileage track, because the mileages are all low and the useful question is what's arriving month by month. The day count runs from the first complaint NHTSA received, not from the on-sale date.
What can go wrong
Owners file after something bad happened, so every count is biased toward failure. Counts jump after news coverage or an investigation. A recall on a system is not proof that a complaint on the same system is the recalled failure. And a word pattern is a blunt instrument: a complaint about a sticking door can land in a group about sticking steering if it mentions both. When in doubt, read the owners' own words on the page.