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Triumph Stag v8 vs Triumph Unknown: reliability comparison

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

Triumph Stag v8
84%
MOT pass rate · 4 vehicles
Triumph Unknown
89%
MOT pass rate · 65,927 vehicles
Verdict: On MOT pass rate the Triumph Stag v8 (84%) and Triumph Unknown (89%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Head to head

Measure Triumph Stag v8 Triumph Unknown
MOT pass rate 84% 89% ✓
MOT failure rate 16% 11% ✓
Faults & advisories per test 1.2 0.6 ✓
Dangerous-fault share 4% 2% ✓
Average mileage 66,796 mi 16,601 mi
Sample size (vehicles) 4 65,927

Most common faults

Triumph Stag v8

  1. Oil leak, but not excessive (8.4.1 (a) (i))
  2. Oil leak
  3. Parking brake efficiency less than 50% of the required value (1.4.2 (a) (ii))
  4. Nearside Rear Tyre worn close to the legal limit (4.1.E.1)
  5. Exhaust noisy (7.1.4)
  6. clutch hydraulic pipe chaffing, some traces of fluid around slave cylinder.

Triumph Unknown

  1. Exhaust noisy (8.1.1 (a))
  2. Exhaust noisy (7.1.2)
  3. Front Roller brake test indicates slight fluctuation of brake effort (3.3.A1d)
  4. COVID-19 6 MONTH EXTENSION
  5. Rear Tyre worn close to the legal limit (5.2.3 (e))
  6. Steering headbearing has slight free play (2.2.2)

Reliability FAQ

On MOT pass rate the Triumph Stag v8 (84%) and Triumph Unknown (89%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Full Triumph Stag v8 report Full Triumph 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.