A search for a used car can turn up pages of complaints, investigations, and service bulletins. Reading them can be worthwhile. Counting them and deciding the car must be bad is a much weaker use of the information.
NHTSA's records serve different purposes. The useful task is to work out what each record establishes and whether it raises a question about the vehicle you are considering.
Start with the record type
An owner complaint describes a reported experience. It may help identify a pattern worth investigating, but it is not a finding that every vehicle has the same defect.
An investigation shows that the agency is examining a potential issue. Read its scope, status, and available findings. An open investigation and a completed recall are different stages with different implications.
Manufacturer communications include service information and bulletins. A bulletin can help a technician identify a condition or repair procedure. Its existence does not establish that your car has the condition or that every related repair will be free.
A recall carries its own description, affected population, and remedy information. Apply those details to the specific VIN when resolving a purchase.
Raw complaint totals need context
Suppose one model has more complaints than another. How many of each are on the road? How old are they? How much have they been driven? Are you seeing distinct events or records describing related issues?
Without that context, the count does not become a failure rate. Ten descriptions of a similar problem may justify investigation, but they do not tell you the percentage of vehicles that will experience it.
Severity matters too. A recurring inconvenience and a report of a serious safety problem should not receive equal weight simply because both occupy one row in a database.
Turn the research into a useful question
Identify the particular year, equipment, symptom, and production range where the record provides them. If a concern appears relevant, share it with the inspecting technician and look for service documentation. A focused question gives the research somewhere to go.
For example, “Does this bulletin apply to this VIN, and is there evidence the relevant work was done?” is more useful than announcing that the model has a long list of problems. Sometimes the answer will remove a concern. Sometimes it will justify more investigation or choosing another car.
Use the records to improve the quality of your decision. They are most valuable when they lead back to evidence about the car you might buy.