2020 Mercedes-Benz S-Class — MOT failures & pass rate
2,394 MOT tests on the 2020 Mercedes-Benz S-Class are in this dataset, and 93.4% of them passed. Executive cars of a similar age fail 9.6% of the time, so this is 3.0pp better than the group it competes with. Failures cluster in tyres, brakes and lighting & signalling.
What the MOT record shows
One area stands out: tyres, recorded in 4.6% of tests against 0.9% for the next-worst category.
At component level the recurring items are tread depth, brake pads and headlamp aim — tread depth alone was recorded 44 times.
Condition tracks the odometer closely. Failures run at 5.0% in the 0-30k band and 9.1% in the 150k+ band, a 4.1-point spread.
Tyres is the most common advisory, noted on 17.1% of tests — work that passed today but is likely due soon.
The trend is worsening — 0.0% of tests failed in 2021 against 6.3% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.6% | 110 |
| 2 | Brakes | 0.9% | 22 |
| 3 | Lighting & signalling | 0.9% | 22 |
| 4 | Visibility | 0.7% | 17 |
| 5 | Suspension | 0.5% | 12 |
| 6 | Other defects | 0.4% | 10 |
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 | 44 |
| 2 | Brake pads | 22 |
| 3 | Headlamp aim | 17 |
| 4 | Registration plates | 16 |
| 5 | Washers | 13 |
| 6 | Ball joint | 13 |
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 | 17.1% | 410 |
| 2 | Brakes | 7.7% | 185 |
| 3 | Visibility | 2.6% | 63 |
| 4 | Other defects | 2.5% | 59 |
| 5 | Suspension | 1.6% | 37 |
| 6 | Road wheels | 0.9% | 21 |
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 | 822 | 5.0% |
| 30-60k | 957 | 8.2% |
| 60-90k | 373 | 6.2% |
| 90-120k | 163 | 5.5% |
| 120-150k | 46 | 10.9% |
| 150k+ | 33 | 9.1% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 1,813 | 7.1% |
| Hybrid | 342 | 5.9% |
| Petrol | 239 | 4.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 55 | 0.0% |
| 2022 | 160 | 1.9% |
| 2023 | 749 | 7.3% |
| 2024 | 737 | 7.7% |
| 2025 | 693 | 6.3% |
What to check before buying a 2020 S-Class
The failure pattern for this year is specific enough to inspect against: tyres accounted for 4.6% of tests. Start there.
- Tyres (4.6% 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 (0.9% 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.
- Lighting & signalling (0.9% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£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 S-Classs pass their MOT?
93.4% of the 2,394 2020 Mercedes-Benz S-Class MOT tests in this dataset passed — a 6.6% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz S-Class?
Tyres, recorded in 4.6% of tests, followed by brakes (0.9%).
Does the 2020 S-Class get worse with mileage?
Its MOT fail rate rises from 5.0% in the 0-30k band to 9.1% in the 150k+ band.
Methodology & source. Based on 2,394 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.