2020 Mercedes-Benz A-Class — MOT failures & pass rate
118,106 MOT tests on the 2020 Mercedes-Benz A-Class are in this dataset, and 91.3% of them passed. That is effectively the same as small family cars of a similar age (8.9% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in tyres, brakes and visibility.
What the MOT record shows
One area stands out: tyres, recorded in 5.1% of tests against 1.7% for the next-worst category.
At component level the recurring items are tread depth, brake pads and headlamp aim — tread depth alone was recorded 2,507 times.
Mileage is the strongest signal on the record: 6.4% of 0-30k cars fail, rising to 18.8% once past 150k — 2.9× the risk.
Fuel type barely separates them — petrol fails 8.4% of the time against 9.8% for diesel.
Tyres is the most common advisory, noted on 22.6% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 13.6% in 2021 to 9.6% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 5.1% | 6,002 |
| 2 | Brakes | 1.7% | 1,994 |
| 3 | Visibility | 1.7% | 1,950 |
| 4 | Lighting & signalling | 1.4% | 1,660 |
| 5 | Suspension | 0.8% | 974 |
| 6 | Emissions & environmental | 0.6% | 734 |
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 | 2,507 |
| 2 | Brake pads | 1,941 |
| 3 | Headlamp aim | 1,677 |
| 4 | Wipers | 1,185 |
| 5 | Washers | 915 |
| 6 | Malfunction indicator lamp | 603 |
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 | 22.6% | 26,656 |
| 2 | Brakes | 10.0% | 11,855 |
| 3 | Other defects | 4.9% | 5,826 |
| 4 | Visibility | 3.1% | 3,705 |
| 5 | Suspension | 1.5% | 1,813 |
| 6 | Road wheels | 0.4% | 514 |
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 | 56,692 | 6.4% |
| 30-60k | 51,485 | 10.6% |
| 60-90k | 8,630 | 12.1% |
| 90-120k | 1,107 | 11.7% |
| 120-150k | 154 | 11.7% |
| 150k+ | 32 | 18.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 75,629 | 8.4% |
| Diesel | 22,221 | 9.8% |
| Hybrid | 20,256 | 8.7% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 44 | 13.6% |
| 2022 | 1,283 | 5.4% |
| 2023 | 39,456 | 8.2% |
| 2024 | 38,510 | 8.4% |
| 2025 | 38,813 | 9.6% |
What to check before buying a 2020 A-Class
The failure pattern for this year is specific enough to inspect against: tyres accounted for 5.1% of tests. Start there.
- Tyres (5.1% 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.
- Brakes (1.7% 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.
- Visibility (1.7% 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 A-Classs pass their MOT?
91.3% of the 118,106 2020 Mercedes-Benz A-Class MOT tests in this dataset passed — a 8.7% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz A-Class?
Tyres, recorded in 5.1% of tests, followed by brakes (1.7%).
Does the 2020 A-Class get worse with mileage?
Its MOT fail rate rises from 6.4% in the 0-30k band to 18.8% in the 150k+ band.
Methodology & source. Based on 118,106 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.