Bentley Derby vs Bentley Unknown: reliability comparison
MOT pass rates, common faults and mileage compared from real UK MOT data.
Bentley Derby
93%
MOT pass rate · 120 vehicles
More reliable
Bentley Unknown
90%
MOT pass rate · 9,548 vehicles
Verdict: On MOT pass rate, the Bentley Derby is the more reliable of the two — 93% pass first time versus 90%. It's one signal among several; check the full breakdown below.
Head to head
| Measure | Bentley Derby | Bentley Unknown |
|---|---|---|
| MOT pass rate | 93% ✓ | 90% |
| MOT failure rate | 7% ✓ | 10% |
| Faults & advisories per test | 0.5 ✓ | 0.9 |
| Dangerous-fault share | 0% ✓ | 7% |
| Average mileage | 58,748 mi | 34,409 mi |
| Sample size (vehicles) | 120 | 9,548 |
Most common faults
Bentley Derby
- Oil leak
- Nearside Front Axle king pin has slight play in pin and/or bush (2.5.A.3a)
- Offside Front Axle king pin has slight play in pin and/or bush (2.5.A.3a)
- Steering system has slight free play detected at steering wheel (2.2.A.1a)
- Ball joint has slight play (2.2.B.1f)
- Front Axle king pin has slight play in pin and/or bush (2.5.A.3a)
Bentley Unknown
- COVID-19 6 MONTH EXTENSION
- Parking brake efficiency less than 50% of the required value (1.4.2 (a) (ii))
- Parking brake: efficiency below requirements (3.7.B.7)
- Windscreen washer provides insufficient washer liquid (8.2.3)
- Oil leak
- Offside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
Reliability FAQ
On MOT pass rate, the Bentley Derby is the more reliable of the two — 93% pass first time versus 90%. It's one signal among several; check the full breakdown below.
Full Bentley Derby report Full Bentley Unknown report Most reliable cars
Pass rates are computed over completed (pass/fail) MOT tests. Reliability also depends on age, mileage and upkeep — see each model's page for the full picture.