One report can mention several components.
NHTSA’s bulk file can repeat a complaint across multiple component rows. Recallfolio groups those rows by ODI number within each model-year. A report mentioning both the engine and the electrical system counts once in the total and once in each of those categories.
For that reason, adding category counts can exceed the total number of distinct reports. “Most-reported category” describes this dataset; it does not establish the most common failure among all vehicles on the road.
The missing denominator matters.
Imagine two model years with 300 and 100 reports. If the first sold many more vehicles, or has been driven for many more years, the difference could mean something very different from a threefold failure risk. This dataset does not provide a consistent exposure measure for the comparisons we publish.
We therefore do not create reliability scores, rank “best” years or convert complaints into a failure percentage. Our comparison tool keeps the underlying counts visible with this limitation alongside them.
Mileage describes reports, not a lifespan.
Where supplied, the median mileage describes the middle of the reported mileage values. It does not predict when a problem will begin or when a vehicle will fail. Missing mileage and inaccurate entries can change the picture. We exclude zero, negative and implausibly high values above one million miles rather than replacing them with guesses.
The timeline is when reports were filed.
A problem can be reported well after it occurs. The timeline on a dossier uses the received date in the source and shows the latest 15 years with reports. It is not a chart of incident dates, and an increase is not automatically evidence that a defect became more prevalent.
Separate a pattern from a proven link.
A complaint and a bulletin can mention the same broad component without describing the same issue. Recallfolio does not claim that a manufacturer fixed an owner-reported symptom merely because both records list the engine or transmission.
Read the campaign or communication, verify the exact applicability, and ask a qualified inspector about the individual car. The strongest next step is a specific question supported by a source.