2020 Mercedes-Benz C-Class — MOT failures & pass rate
34,731 MOT tests on the 2020 Mercedes-Benz C-Class are in this dataset, and 89.8% of them passed. That is effectively the same as executive cars of a similar age (10.0% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in tyres, lighting & signalling and visibility.
What the MOT record shows
One area stands out: tyres, recorded in 7.3% of tests against 1.3% for the next-worst category.
At component level the recurring items are tread depth, headlamp aim and brake pads — tread depth alone was recorded 1,293 times.
Mileage matters less than usual here: the 2020 C-Class fails 7.9% of the time in the 0-30k band and 5.3% at 150k+, a spread of only 2.6 points.
The hybrid cars hold up better: 9.0% fail against 10.7% for diesel, a 1.6-point gap across 28,357 tests.
Tyres is the most common advisory, noted on 24.0% of tests — work that passed today but is likely due soon.
The trend is worsening — 8.0% of tests failed in 2021 against 11.3% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.3% | 2,552 |
| 2 | Lighting & signalling | 1.3% | 448 |
| 3 | Visibility | 1.3% | 445 |
| 4 | Brakes | 1.1% | 378 |
| 5 | Suspension | 0.9% | 319 |
| 6 | Road wheels | 0.8% | 268 |
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 | 1,293 |
| 2 | Headlamp aim | 529 |
| 3 | Brake pads | 350 |
| 4 | Wipers | 295 |
| 5 | Washers | 197 |
| 6 | Registration plates | 192 |
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 | 24.0% | 8,325 |
| 2 | Brakes | 9.5% | 3,290 |
| 3 | Other defects | 4.1% | 1,431 |
| 4 | Visibility | 3.2% | 1,107 |
| 5 | Suspension | 2.4% | 838 |
| 6 | Body, structure & corrosion | 1.8% | 613 |
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 | 15,273 | 7.9% |
| 30-60k | 15,504 | 11.4% |
| 60-90k | 3,294 | 13.8% |
| 90-120k | 515 | 15.9% |
| 120-150k | 103 | 13.6% |
| 150k+ | 38 | 5.3% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 18,457 | 10.7% |
| Hybrid | 9,900 | 9.0% |
| Petrol | 6,365 | 10.5% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 50 | 8.0% |
| 2022 | 682 | 5.6% |
| 2023 | 11,765 | 10.0% |
| 2024 | 11,142 | 9.5% |
| 2025 | 11,092 | 11.3% |
What to check before buying a 2020 C-Class
The failure pattern for this year is specific enough to inspect against: tyres accounted for 7.3% of tests. Start there.
- Tyres (7.3% 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.
- Lighting & signalling (1.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (1.3% of tests): Wipers, washers, mirrors and screen damage — usually inexpensive, but check for chips in the driver's line of sight. Typical repair: £15–£150.
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 2020 Mercedes-Benz C-Classs pass their MOT?
89.8% of the 34,731 2020 Mercedes-Benz C-Class MOT tests in this dataset passed — a 10.2% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz C-Class?
Tyres, recorded in 7.3% of tests, followed by lighting & signalling (1.3%).
Does the 2020 C-Class get worse with mileage?
Its MOT fail rate rises from 7.9% in the 0-30k band to 5.3% in the 150k+ band.
Methodology & source. Based on 34,731 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.