2018 Mercedes-Benz CLA — MOT failures & pass rate
Across 48,113 MOT tests, the 2018 Mercedes-Benz CLA recorded an 87.6% pass rate. That is 2.0 percentage points worse than small family cars of a similar age, which fail at 10.4%. Failures cluster in tyres, visibility and brakes.
What the MOT record shows
Tyres dominates the failure mix at 7.6% of all tests — 4.7 points clear of visibility, so it is the first thing to check.
At component level the recurring items are tread depth, brake pads and washers — tread depth alone was recorded 1,291 times.
Condition tracks the odometer closely. Failures run at 8.6% in the 0-30k band and 17.0% in the 150k+ band, a 8.4-point spread.
Fuel type barely separates them — petrol fails 12.0% of the time against 12.8% for diesel.
Advisories point at the next bill rather than this one: tyres was flagged on 26.0% of tests without failing them.
The trend is worsening — 10.6% of tests failed in 2021 against 14.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.6% | 3,647 |
| 2 | Visibility | 2.9% | 1,377 |
| 3 | Brakes | 2.3% | 1,105 |
| 4 | Lighting & signalling | 2.2% | 1,060 |
| 5 | Emissions & environmental | 1.1% | 538 |
| 6 | Road wheels | 0.9% | 438 |
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 | 1,291 |
| 2 | Brake pads | 975 |
| 3 | Washers | 882 |
| 4 | Headlamp aim | 732 |
| 5 | Wipers | 637 |
| 6 | Malfunction indicator lamp | 508 |
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 | 26.0% | 12,495 |
| 2 | Brakes | 14.9% | 7,167 |
| 3 | Other defects | 6.6% | 3,166 |
| 4 | Visibility | 3.0% | 1,460 |
| 5 | Road wheels | 1.7% | 807 |
| 6 | Lighting & signalling | 1.4% | 655 |
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 | 14,315 | 8.6% |
| 30-60k | 23,772 | 12.9% |
| 60-90k | 8,081 | 16.0% |
| 90-120k | 1,605 | 17.9% |
| 120-150k | 276 | 18.1% |
| 150k+ | 59 | 17.0% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 27,321 | 12.0% |
| Diesel | 20,792 | 12.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 9,859 | 10.6% |
| 2022 | 9,535 | 10.4% |
| 2023 | 9,565 | 12.6% |
| 2024 | 9,490 | 13.6% |
| 2025 | 9,664 | 14.6% |
What to check before buying a 2018 CLA
On a 2018 CLA, tyres is what the MOT record says goes wrong most — it appeared in 7.6% of tests. Check these areas before you commit.
- Tyres (7.6% 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.
- 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 (2.3% 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 2018 Mercedes-Benz CLAs pass their MOT?
87.6% of the 48,113 2018 Mercedes-Benz CLA MOT tests in this dataset passed — a 12.4% fail rate.
What is the most common MOT failure on a 2018 Mercedes-Benz CLA?
Tyres, recorded in 7.6% of tests, followed by visibility (2.9%).
Does the 2018 CLA get worse with mileage?
Its MOT fail rate rises from 8.6% in the 0-30k band to 17.0% in the 150k+ band.
Methodology & source. Based on 48,113 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.