2017 Mercedes-Benz CLS — MOT failures & pass rate
8,626 MOT tests on the 2017 Mercedes-Benz CLS are in this dataset, and 86.7% of them passed. Against executive cars of a similar age (11.6% fail rate), the 2017 CLS comes out 1.7pp worse. Failures cluster in tyres, brakes and emissions & environmental.
What the MOT record shows
One area stands out: tyres, recorded in 8.6% of tests against 2.7% for the next-worst category.
At component level the recurring items are tread depth, malfunction indicator lamp and headlamp aim — tread depth alone was recorded 185 times.
A 150k+ example is materially riskier than a 0-30k one: 20.0% versus 9.8%.
Tyres is the most common advisory, noted on 22.7% of tests — work that passed today but is likely due soon.
The trend is worsening — 11.0% of tests failed in 2021 against 15.2% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 8.6% | 741 |
| 2 | Brakes | 2.7% | 230 |
| 3 | Emissions & environmental | 1.8% | 159 |
| 4 | Suspension | 1.7% | 144 |
| 5 | Lighting & signalling | 1.6% | 134 |
| 6 | Road wheels | 1.0% | 88 |
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 | 185 |
| 2 | Malfunction indicator lamp | 148 |
| 3 | Headlamp aim | 137 |
| 4 | Coil spring | 101 |
| 5 | Brake pads | 94 |
| 6 | Registration plates | 67 |
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 | 22.7% | 1,956 |
| 2 | Brakes | 13.2% | 1,139 |
| 3 | Suspension | 5.6% | 486 |
| 4 | Other defects | 4.7% | 409 |
| 5 | Visibility | 2.5% | 215 |
| 6 | Road wheels | 1.8% | 159 |
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 | 1,818 | 9.8% |
| 30-60k | 4,031 | 12.9% |
| 60-90k | 1,995 | 15.4% |
| 90-120k | 588 | 17.5% |
| 120-150k | 143 | 18.9% |
| 150k+ | 50 | 20.0% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 8,372 | 13.3% |
| Petrol | 254 | 15.0% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,732 | 11.0% |
| 2022 | 1,708 | 11.9% |
| 2023 | 1,736 | 13.0% |
| 2024 | 1,750 | 15.3% |
| 2025 | 1,700 | 15.2% |
What to check before buying a 2017 CLS
The failure pattern for this year is specific enough to inspect against: tyres accounted for 8.6% of tests. Start there.
- Tyres (8.6% 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 (2.7% 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.
- Emissions & environmental (1.8% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
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 2017 Mercedes-Benz CLSs pass their MOT?
86.7% of the 8,626 2017 Mercedes-Benz CLS MOT tests in this dataset passed — a 13.3% fail rate.
What is the most common MOT failure on a 2017 Mercedes-Benz CLS?
Tyres, recorded in 8.6% of tests, followed by brakes (2.7%).
Does the 2017 CLS get worse with mileage?
Its MOT fail rate rises from 9.8% in the 0-30k band to 20.0% in the 150k+ band.
Methodology & source. Based on 8,626 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.