Audi A4 vs Audi A6 s line tdi: reliability comparison
MOT pass rates, common faults and mileage compared from real UK MOT data.
Audi A4
76%
MOT pass rate · 568,515 vehicles
Audi A6 s line tdi
88%
MOT pass rate · 1,562 vehicles
More reliable
Verdict: On MOT pass rate, the Audi A6 s line tdi is the more reliable of the two — 88% pass first time versus 76%. It's one signal among several; check the full breakdown below.
Head to head
| Measure | Audi A4 | Audi A6 s line tdi |
|---|---|---|
| MOT pass rate | 76% | 88% ✓ |
| MOT failure rate | 24% | 12% ✓ |
| Faults & advisories per test | 1.9 | 0.0 ✓ |
| Dangerous-fault share | 2% | 0% ✓ |
| Average mileage | 133,841 mi | 165,129 mi |
| Sample size (vehicles) | 568,515 | 1,562 |
Most common faults
Audi A4
- 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)
- 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 legal limit/worn on edge (5.2.3 (e))
Audi A6 s line tdi
- Nearside Front Brake disc worn, but not excessively (1.1.14 (a) (i))
- Nearside Front Brake hose has slight corrosion to ferrule (1.1.12 (f) (i))
- Nearside Front Brake pad(s) wearing thin (1.1.13 (a) (ii))
- Offside Front Brake disc worn, but not excessively (1.1.14 (a) (i))
- Offside Front Brake pad(s) wearing thin (1.1.13 (a) (ii))
- Oil leak, but not excessive (8.4.1 (a) (i))
Reliability FAQ
On MOT pass rate, the Audi A6 s line tdi is the more reliable of the two — 88% pass first time versus 76%. It's one signal among several; check the full breakdown below.
Full Audi A4 report Full Audi A6 s line 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.