2020 Mercedes-Benz CLA — MOT failures & pass rate
The 2020 Mercedes-Benz CLA passed 89.1% of its 25,188 recorded MOT tests. Small family cars of a similar age fail 8.9% of the time, so this is 1.9pp worse than the group it competes with. Failures cluster in tyres, lighting & signalling and brakes.
What the MOT record shows
One area stands out: tyres, recorded in 6.8% of tests against 2.3% for the next-worst category.
At component level the recurring items are tread depth, headlamp aim and brake pads — tread depth alone was recorded 636 times.
Mileage matters less than usual here: the 2020 CLA fails 8.5% of the time in the 0-30k band and 4.9% at 120-150k, a spread of only 3.6 points.
The hybrid cars hold up better: 8.8% fail against 11.5% for petrol, a 2.7-point gap across 20,457 tests.
Tyres is the most common advisory, noted on 25.9% of tests — work that passed today but is likely due soon.
The trend is worsening — 7.3% of tests failed in 2022 against 11.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.8% | 1,722 |
| 2 | Lighting & signalling | 2.3% | 579 |
| 3 | Brakes | 2.2% | 553 |
| 4 | Visibility | 1.9% | 476 |
| 5 | Suspension | 0.8% | 205 |
| 6 | Other defects | 0.5% | 129 |
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 | 636 |
| 2 | Headlamp aim | 588 |
| 3 | Brake pads | 576 |
| 4 | Wipers | 267 |
| 5 | Washers | 230 |
| 6 | Registration plates | 204 |
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 | 25.9% | 6,524 |
| 2 | Brakes | 11.7% | 2,949 |
| 3 | Other defects | 5.4% | 1,371 |
| 4 | Visibility | 3.8% | 954 |
| 5 | Suspension | 1.5% | 380 |
| 6 | Lighting & signalling | 1.1% | 286 |
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 | 10,473 | 8.5% |
| 30-60k | 11,972 | 12.3% |
| 60-90k | 2,356 | 13.8% |
| 90-120k | 330 | 14.5% |
| 120-150k | 41 | 4.9% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 17,520 | 11.5% |
| Diesel | 4,731 | 10.0% |
| Hybrid | 2,937 | 8.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2022 | 246 | 7.3% |
| 2023 | 8,384 | 10.3% |
| 2024 | 8,221 | 10.8% |
| 2025 | 8,327 | 11.6% |
What to check before buying a 2020 CLA
The failure pattern for this year is specific enough to inspect against: tyres accounted for 6.8% of tests. Start there.
- Tyres (6.8% 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 (2.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (2.2% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
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 CLAs pass their MOT?
89.1% of the 25,188 2020 Mercedes-Benz CLA MOT tests in this dataset passed — a 10.9% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz CLA?
Tyres, recorded in 6.8% of tests, followed by lighting & signalling (2.3%).
Does the 2020 CLA get worse with mileage?
Its MOT fail rate rises from 8.5% in the 0-30k band to 4.9% in the 120-150k band.
Methodology & source. Based on 25,188 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.