Mercedes-Benz S350d — MOT pass rate & failures
The Mercedes-Benz S350d passed 93.3% of its 3,226 MOT tests, covering model years 2010–2025. That is 6.4 percentage points better than the 13.1% fail rate across all Mercedes-Benz S-Class versions, so the S350d is a stronger pick within the range. Failures concentrate in tyres, brakes and suspension.
What the MOT record shows
At component level the recurring items are tread depth, brake pads and ball joint — tread depth alone was recorded 52 times.
Mileage matters less than usual here: the S350d fails 5.5% of the time in the 0-30k band and 8.8% at 150k+, a spread of only 3.2 points.
Advisories point at the next bill rather than this one: tyres was flagged on 16.5% of tests without failing them.
How it compares
By model year
| Year | Tests | Pass rate | Fail rate |
|---|---|---|---|
| 2010 | 31 | 90.3% | 9.7% |
| 2017 | 33 | 90.9% | 9.1% |
| 2019 | 353 | 93.5% | 6.5% |
| 2020 | 1,423 | 92.5% | 7.5% |
| 2021 | 978 | 94.5% | 5.5% |
| 2022 | 175 | 93.1% | 6.9% |
| 2023 | 88 | 94.3% | 5.7% |
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.5% | 144 |
| 2 | Brakes | 1.0% | 31 |
| 3 | Suspension | 0.7% | 23 |
| 4 | Lighting & signalling | 0.7% | 22 |
| 5 | Visibility | 0.7% | 22 |
| 6 | Emissions & environmental | 0.6% | 19 |
| 7 | Other defects | 0.4% | 12 |
| 8 | Road wheels | 0.3% | 11 |
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 | 52 |
| 2 | Brake pads | 29 |
| 3 | Ball joint | 26 |
| 4 | Headlamp aim | 21 |
| 5 | Registration plates | 21 |
| 6 | Malfunction indicator lamp | 17 |
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 | 16.5% | 533 |
| 2 | Brakes | 8.2% | 264 |
| 3 | Visibility | 2.5% | 82 |
| 4 | Suspension | 2.5% | 80 |
| 5 | Other defects | 1.9% | 63 |
| 6 | Road wheels | 0.7% | 22 |
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 | 1,066 | 5.5% |
| 30-60k | 1,238 | 7.8% |
| 60-90k | 530 | 6.4% |
| 90-120k | 234 | 5.1% |
| 120-150k | 100 | 10.0% |
| 150k+ | 57 | 8.8% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 68 | 7.3% |
| 2022 | 275 | 4.7% |
| 2023 | 721 | 6.8% |
| 2024 | 1,025 | 7.1% |
| 2025 | 1,137 | 6.8% |
What to check before buying a Mercedes-Benz S350d
Focus on the areas it most often fails on — and remember MOT data covers testable defects only, not engine or gearbox health.
- Tyres (4.5% 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.
- Brakes (1.0% 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.
- Suspension (0.7% 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.
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 reliable is the Mercedes-Benz S350d at MOT time?
93.3% of the 3,226 Mercedes-Benz S350d MOT tests in this dataset passed — a 6.7% fail rate, better than the 13.1% average across all S-Class versions.
What is the most common MOT failure on a Mercedes-Benz S350d?
Tyres, recorded in 4.5% of tests, followed by brakes (1.0%).
Does the S350d get worse with mileage?
Its MOT fail rate rises from 5.5% in the 0-30k band to 8.8% in the 150k+ band.
Methodology & source. Based on 3,226 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.