Porsche 356 90 vs Porsche 911: reliability comparison
MOT pass rates, common faults and mileage compared from real UK MOT data.
Porsche 356 90
91%
MOT pass rate · 1 vehicles
Porsche 911
85%
MOT pass rate · 74,656 vehicles
Verdict: On MOT pass rate the Porsche 356 90 (91%) and Porsche 911 (85%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.
Head to head
| Measure | Porsche 356 90 | Porsche 911 |
|---|---|---|
| MOT pass rate | 91% ✓ | 85% |
| MOT failure rate | 9% ✓ | 15% |
| Faults & advisories per test | 0.6 ✓ | 1.1 |
| Dangerous-fault share | 0% ✓ | 1% |
| Average mileage | 52,299 mi | 70,982 mi |
| Sample size (vehicles) | 1 | 74,656 |
Most common faults
Porsche 356 90
- Nearside Front Brake hose slightly chafed (1.1.12 (b) (i))
- Offside Front Brake hose slightly chafed (1.1.12 (b) (i))
- Brakes imbalanced requirements only just met. It would appear that the braking system requires adjustment or repair. (3.7.B.5b)
- Offside rear brake grabbing slightly (3.7.A.5b)
- Nearside Front Direction indicator not working (4.4.1 (a) (ii))
Porsche 911
- Nearside Rear Tyre worn close to the legal limit (4.1.E.1)
- Offside Rear Tyre worn close to the legal limit (4.1.E.1)
- Under-trays fitted obscuring some underside components
- Nearside Front Tyre worn close to the legal limit (4.1.E.1)
- Offside Front Tyre worn close to the legal limit (4.1.E.1)
- Oil leak, but not excessive (8.4.1 (a) (i))
Reliability FAQ
On MOT pass rate the Porsche 356 90 (91%) and Porsche 911 (85%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.
Full Porsche 356 90 report Full Porsche 911 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.