2017 Mercedes-Benz C-Class — MOT failures & pass rate
Across 227,716 MOT tests, the 2017 Mercedes-Benz C-Class recorded an 88.2% pass rate. That is effectively the same as executive cars of a similar age (11.6% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in tyres, suspension and emissions & environmental.
What the MOT record shows
One area stands out: tyres, recorded in 6.5% of tests against 2.8% for the next-worst category.
At component level the recurring items are tread depth, ball joint and malfunction indicator lamp — tread depth alone was recorded 9,189 times.
Condition tracks the odometer closely. Failures run at 7.6% in the 0-30k band and 13.8% in the 150k+ band, a 6.2-point spread.
The petrol cars hold up better: 10.0% fail against 12.6% for diesel, a 2.6-point gap across 213,043 tests.
Tyres is the most common advisory, noted on 24.1% of tests — work that passed today but is likely due soon.
The trend is worsening — 9.3% of tests failed in 2021 against 13.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.5% | 14,804 |
| 2 | Suspension | 2.8% | 6,312 |
| 3 | Emissions & environmental | 1.9% | 4,374 |
| 4 | Lighting & signalling | 1.6% | 3,714 |
| 5 | Brakes | 1.5% | 3,501 |
| 6 | Visibility | 1.4% | 3,143 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Tread depth | 9,189 |
| 2 | Ball joint | 4,326 |
| 3 | Malfunction indicator lamp | 4,128 |
| 4 | Headlamp aim | 3,518 |
| 5 | Brake pads | 2,988 |
| 6 | Coil spring | 2,564 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 24.1% | 54,781 |
| 2 | Brakes | 13.4% | 30,611 |
| 3 | Suspension | 5.4% | 12,270 |
| 4 | Other defects | 4.9% | 11,093 |
| 5 | Visibility | 3.1% | 7,078 |
| 6 | Body, structure & corrosion | 0.9% | 2,125 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 42,962 | 7.6% |
| 30-60k | 107,592 | 11.4% |
| 60-90k | 54,564 | 14.5% |
| 90-120k | 16,452 | 15.3% |
| 120-150k | 4,263 | 15.1% |
| 150k+ | 1,837 | 13.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 150,736 | 12.6% |
| Petrol | 62,307 | 10.0% |
| Hybrid | 14,673 | 11.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 45,844 | 9.3% |
| 2022 | 45,611 | 10.6% |
| 2023 | 45,691 | 12.2% |
| 2024 | 45,477 | 13.3% |
| 2025 | 45,093 | 13.6% |
What to check before buying a 2017 C-Class
The failure pattern for this year is specific enough to inspect against: tyres accounted for 6.5% of tests. Start there.
- Tyres (6.5% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Suspension (2.8% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Emissions & environmental (1.9% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2017 Mercedes-Benz C-Classs pass their MOT?
88.2% of the 227,716 2017 Mercedes-Benz C-Class MOT tests in this dataset passed — a 11.8% fail rate.
What is the most common MOT failure on a 2017 Mercedes-Benz C-Class?
Tyres, recorded in 6.5% of tests, followed by suspension (2.8%).
Does the 2017 C-Class get worse with mileage?
Its MOT fail rate rises from 7.6% in the 0-30k band to 13.8% in the 150k+ band.
Methodology & source. Based on 227,716 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.