How We Rate
Every weakness on this site was individually researched and verified. Here we explain transparently how our ratings are created.
Data Sources
Our weakness database is built from multiple independent sources:
- TÜV Reports — Annual defect statistics from German vehicle inspections
- ADAC Breakdown Statistics — Real breakdown data from millions of roadside assists
- NHTSA Complaints (US) — Complaints filed by American vehicle owners
- Specialist Forums — motor-talk.de, bimmerpost.com, reddit.com/r/MechanicAdvice and others
- Recall Databases — KBA (Germany), NHTSA (USA)
- Workshop Experience — Documented repair cases from specialist workshops
Rating Scale: Severity
| Level | Meaning |
|---|---|
| 5 | Critical — total loss, fire risk, or safety hazard |
| 4 | High — expensive repair, potential breakdown |
| 3 | Medium — noticeable impact, moderate cost |
| 2 | Low — annoying but cheap to fix |
| 1 | Minimal — wear part, normal aging |
Overall Engine Rating
The overall engine rating (Good Choice, Caution, or Stay Away) is automatically calculated from all documented weaknesses. Severity and probability of each weakness flow into the score.
We do not set ratings manually. An engine with many minor weaknesses can still be rated "Good Choice", while an engine with a single critical weakness may fall to "Stay Away".
Editorial Process
Every buying guide (the editorial text at the top of each page) is written by hand — not generated. AI tools assist with structured data capture and translation, but the editorial judgment and assessment is human.
Found an error or a missing weakness? Let us know.