In depth

• Why modern engines burn oil, and what owner complaints revealDesign choices linked to oil consumption in recent engines, the warning signs owners describe, what counts as normal, and which tracked models currently have the highest engine share in their complaints.
• Transmission problems explained: shudder, harsh shifts, CVTs and what to test on a driveHow the main automatic transmission types fail, the symptoms owner complaints describe for each, and a practical test-drive checklist.
• Phantom braking and other driver-assist complaints: what goes wrong and where the complaints concentrateHow automatic emergency braking, adaptive cruise and lane keeping produce false alarms, which tracked models have the highest share of their own complaints in this category, what NHTSA has investigated, and what to test before buying.
• Stalling and loss of motive power: why a stall at speed is a safety problemWhy a stall at speed is treated as a crash risk, the fuel pump, engine, transmission and high-voltage causes owners report, what to do in the moment, and where the complaints concentrate now.
• From complaint to recall: how an NHTSA defect investigation worksThe stages of a U.S. safety investigation, how long each takes, what the action numbers mean, how manufacturers respond, and which investigations are open right now on the models this site tracks.
• Why the model year matters more than the badge: first-year problems and how to read year-by-year dataHow redesigns, mid-cycle fixes and supplier changes make one model year very different from the next, what first-year complaint patterns look like, and which tracked models show the largest gap between their best and worst years.
• What electric-vehicle owners complain about, compared with gas carsThe complaint categories that dominate EV reports, how they differ from combustion vehicles, why the numbers are skewed by a few brands, and the live problem mix of the electric segment.

Guides

• Using complaint data when buying a used carA practical checklist: read the model trend, find the years to avoid, check problem areas and recall completion, and what to test on the drive.
• How to check whether your car has an open recallStep-by-step: find your VIN, check NHTSA's recall lookup, understand park-outside and do-not-drive warnings, and get a free repair.
• How to file a vehicle safety complaint with NHTSAWhat to include in an NHTSA complaint, how the ODI number works, and how complaint patterns turn into investigations and recalls.
• Glossary: complaints, recalls and investigationsPlain-language definitions of ODI numbers, campaign numbers, park-outside warnings, PE and EA investigations, TSBs, the complaint index and other terms used on this site.
• Frequently asked questionsAnswers about where the data comes from, how often it updates, why sales are not included, how to cite the site and how to use the data programmatically.