2017 Mercedes-Benz CLA — MOT failures & pass rate
Across 47,797 MOT tests, the 2017 Mercedes-Benz CLA recorded an 86.2% pass rate. Against small family cars of a similar age (11.9% fail rate), the 2017 CLA comes out 1.9pp worse. Failures cluster in tyres, visibility and brakes.
What the MOT record shows
One area stands out: tyres, recorded in 7.9% of tests against 2.9% for the next-worst category.
At component level the recurring items are tread depth, brake pads and washers — tread depth alone was recorded 1,447 times.
A 150k+ example is materially riskier than a 0-30k one: 17.5% versus 8.8%.
Fuel type barely separates them — petrol fails 13.2% of the time against 14.2% for diesel.
Tyres is the most common advisory, noted on 26.2% of tests — work that passed today but is likely due soon.
The trend is worsening — 10.4% of tests failed in 2021 against 16.7% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.9% | 3,781 |
| 2 | Visibility | 2.9% | 1,367 |
| 3 | Brakes | 2.6% | 1,242 |
| 4 | Suspension | 2.2% | 1,047 |
| 5 | Lighting & signalling | 2.1% | 1,008 |
| 6 | Emissions & environmental | 1.7% | 806 |
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 | 1,447 |
| 2 | Brake pads | 1,022 |
| 3 | Washers | 963 |
| 4 | Malfunction indicator lamp | 747 |
| 5 | Coil spring | 702 |
| 6 | Headlamp aim | 670 |
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 | 26.2% | 12,498 |
| 2 | Brakes | 17.2% | 8,200 |
| 3 | Other defects | 6.0% | 2,848 |
| 4 | Visibility | 3.3% | 1,558 |
| 5 | Suspension | 2.4% | 1,141 |
| 6 | Road wheels | 1.6% | 779 |
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 | 6,844 | 8.8% |
| 30-60k | 22,534 | 12.7% |
| 60-90k | 13,405 | 16.7% |
| 90-120k | 3,956 | 17.9% |
| 120-150k | 841 | 17.2% |
| 150k+ | 206 | 17.5% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 29,619 | 14.2% |
| Petrol | 18,178 | 13.2% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 9,462 | 10.4% |
| 2022 | 9,425 | 12.3% |
| 2023 | 9,551 | 13.9% |
| 2024 | 9,639 | 15.7% |
| 2025 | 9,720 | 16.7% |
What to check before buying a 2017 CLA
The failure pattern for this year is specific enough to inspect against: tyres accounted for 7.9% of tests. Start there.
- Tyres (7.9% 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.
- Visibility (2.9% 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.
- Brakes (2.6% 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 2017 Mercedes-Benz CLAs pass their MOT?
86.2% of the 47,797 2017 Mercedes-Benz CLA MOT tests in this dataset passed — a 13.8% fail rate.
What is the most common MOT failure on a 2017 Mercedes-Benz CLA?
Tyres, recorded in 7.9% of tests, followed by visibility (2.9%).
Does the 2017 CLA get worse with mileage?
Its MOT fail rate rises from 8.8% in the 0-30k band to 17.5% in the 150k+ band.
Methodology & source. Based on 47,797 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.