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Bentley Mulsanne vs Bentley Unknown: reliability comparison

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

Bentley Mulsanne
85%
MOT pass rate · 1,619 vehicles
Bentley Unknown
90%
MOT pass rate · 9,548 vehicles
More reliable
Verdict: On MOT pass rate, the Bentley Unknown is the more reliable of the two — 90% pass first time versus 85%. It's one signal among several; check the full breakdown below.

Head to head

Measure Bentley Mulsanne Bentley Unknown
MOT pass rate 85% 90% ✓
MOT failure rate 15% 10% ✓
Faults & advisories per test 1.1 0.9 ✓
Dangerous-fault share 1% ✓ 7%
Average mileage 59,444 mi 34,409 mi
Sample size (vehicles) 1,619 9,548

Most common faults

Bentley Mulsanne

  1. Parking brake: efficiency below requirements (3.7.B.7)
  2. Oil leak
  3. Oil leak, but not excessive (8.4.1 (a) (i))
  4. Offside rear parking brake recording little or no effort (3.7.B.6a)
  5. Offside Rear Tyre slightly damaged/cracking or perishing (5.2.3 (d) (ii))
  6. Nearside Rear wheel bearing has slight play (2.6.2)

Bentley Unknown

  1. COVID-19 6 MONTH EXTENSION
  2. Parking brake efficiency less than 50% of the required value (1.4.2 (a) (ii))
  3. Parking brake: efficiency below requirements (3.7.B.7)
  4. Windscreen washer provides insufficient washer liquid (8.2.3)
  5. Oil leak
  6. Offside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))

Reliability FAQ

On MOT pass rate, the Bentley Unknown is the more reliable of the two — 90% pass first time versus 85%. It's one signal among several; check the full breakdown below.

Full Bentley Mulsanne 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.