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Porsche 911 vs Porsche 928 s auto: reliability comparison

MOT pass rates, common faults and mileage compared from real UK MOT data.

Porsche 911
85%
MOT pass rate · 74,656 vehicles
Porsche 928 s auto
70%
MOT pass rate · 789 vehicles
Verdict: On MOT pass rate the Porsche 911 (85%) and Porsche 928 s auto (70%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Head to head

Measure Porsche 911 Porsche 928 s auto
MOT pass rate 85% ✓ 70%
MOT failure rate 15% ✓ 30%
Faults & advisories per test 1.1 ✓ 1.7
Dangerous-fault share 1% 0% ✓
Average mileage 70,982 mi 139,878 mi
Sample size (vehicles) 74,656 789

Most common faults

Porsche 911

  1. Nearside Rear Tyre worn close to the legal limit (4.1.E.1)
  2. Offside Rear Tyre worn close to the legal limit (4.1.E.1)
  3. Under-trays fitted obscuring some underside components
  4. Nearside Front Tyre worn close to the legal limit (4.1.E.1)
  5. Offside Front Tyre worn close to the legal limit (4.1.E.1)
  6. Oil leak, but not excessive (8.4.1 (a) (i))

Porsche 928 s auto

  1. Oil leak
  2. Fuel pipe/s corroded
  3. Offside Rear Rear fog lamp not working (1.3.2b)
  4. Nearside Front Tyre worn close to the legal limit (4.1.E.1)
  5. Offside Front Brake hose slightly deteriorated (3.6.B.4d)
  6. Offside Front Steering rack gaiter split (2.2.D.2d)

Reliability FAQ

On MOT pass rate the Porsche 911 (85%) and Porsche 928 s auto (70%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Full Porsche 911 report Full Porsche 928 s auto 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.