2018 Mercedes-Benz CLS — MOT failures & pass rate
Across 5,668 MOT tests, the 2018 Mercedes-Benz CLS recorded an 87.5% pass rate. Executive cars of a similar age fail 10.8% of the time, so this is 1.7pp worse than the group it competes with. Failures cluster in tyres, road wheels and suspension.
What the MOT record shows
Tyres dominates the failure mix at 7.4% of all tests — 4.8 points clear of road wheels, so it is the first thing to check.
At component level the recurring items are ball joint, tread depth and headlamp aim — ball joint alone was recorded 114 times.
Condition tracks the odometer closely. Failures run at 9.4% in the 0-30k band and 21.4% in the 90-120k band, a 12.1-point spread — more than double.
Split by fuel, petrol examples fail 1.8pp more often than diesel ones (14.0% vs 12.2%) — worth weighing if you have a choice.
Advisories point at the next bill rather than this one: tyres was flagged on 19.7% of tests without failing them.
The trend is worsening — 10.7% of tests failed in 2021 against 13.8% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.4% | 420 |
| 2 | Road wheels | 2.6% | 149 |
| 3 | Suspension | 1.8% | 105 |
| 4 | Lighting & signalling | 1.2% | 69 |
| 5 | Brakes | 1.1% | 61 |
| 6 | Emissions & environmental | 1.0% | 55 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Ball joint | 114 |
| 2 | Tread depth | 81 |
| 3 | Headlamp aim | 79 |
| 4 | Registration plates | 59 |
| 5 | Malfunction indicator lamp | 51 |
| 6 | Brake pads | 46 |
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 | 19.7% | 1,115 |
| 2 | Brakes | 10.7% | 609 |
| 3 | Suspension | 5.7% | 322 |
| 4 | Other defects | 4.4% | 250 |
| 5 | Visibility | 1.9% | 106 |
| 6 | Road wheels | 0.9% | 53 |
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 | 1,976 | 9.4% |
| 30-60k | 2,652 | 13.4% |
| 60-90k | 822 | 15.1% |
| 90-120k | 182 | 21.4% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 4,762 | 12.2% |
| Petrol | 900 | 14.0% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,162 | 10.7% |
| 2022 | 1,154 | 10.1% |
| 2023 | 1,141 | 13.4% |
| 2024 | 1,135 | 14.7% |
| 2025 | 1,076 | 13.8% |
What to check before buying a 2018 CLS
On a 2018 CLS, tyres is what the MOT record says goes wrong most — it appeared in 7.4% of tests. Check these areas before you commit.
- Tyres (7.4% 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.
- Road wheels (2.6% of tests): Damaged or corroded wheels, missing/loose fixings — generally a moderate fix. Typical repair: £80–£250.
- Suspension (1.8% 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 many 2018 Mercedes-Benz CLSs pass their MOT?
87.5% of the 5,668 2018 Mercedes-Benz CLS MOT tests in this dataset passed — a 12.5% fail rate.
What is the most common MOT failure on a 2018 Mercedes-Benz CLS?
Tyres, recorded in 7.4% of tests, followed by road wheels (2.6%).
Does the 2018 CLS get worse with mileage?
Its MOT fail rate rises from 9.4% in the 0-30k band to 21.4% in the 90-120k band.
Methodology & source. Based on 5,668 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.