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Audi A6 vs Audi A8 quattro tdi: reliability comparison

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

Audi A6
78%
MOT pass rate · 246,602 vehicles
Audi A8 quattro tdi
93%
MOT pass rate · 2 vehicles
Verdict: On MOT pass rate the Audi A6 (78%) and Audi A8 quattro tdi (93%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Head to head

Measure Audi A6 Audi A8 quattro tdi
MOT pass rate 78% 93% ✓
MOT failure rate 22% 7% ✓
Faults & advisories per test 1.7 ✓ 1.9
Dangerous-fault share 2% 0% ✓
Average mileage 136,441 mi 187,062 mi
Sample size (vehicles) 246,602 2

Most common faults

Audi A6

  1. Nearside Front Tyre worn close to the legal limit (4.1.E.1)
  2. Offside Front Tyre worn close to the legal limit (4.1.E.1)
  3. Nearside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  4. Offside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  5. Nearside Rear Tyre worn close to the legal limit (4.1.E.1)
  6. Offside Rear Tyre worn close to the legal limit (4.1.E.1)

Audi A8 quattro tdi

  1. Nearside Rear Headlamp lens slightly defective (4.1.1 (b) (i))
  2. Nearside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  3. Offside Front Tyre worn close to legal limit/worn on edge (5.2.3 (e))
  4. Rear Brake pad(s) wearing thin (1.1.13 (a) (ii))
  5. Oil leak, but not excessive (8.4.1 (a) (i))
  6. Central Front Windscreen damaged but not adversely affecting driver's view (3.2 (a) (i))

Reliability FAQ

On MOT pass rate the Audi A6 (78%) and Audi A8 quattro tdi (93%) are very close — weigh the individual measures below, and remember condition depends on age, mileage and upkeep.

Full Audi A6 report Full Audi A8 quattro tdi 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.