2014 Mercedes-Benz SLK — MOT failures & pass rate
28,281 MOT tests on the 2014 Mercedes-Benz SLK are in this dataset, and 85.2% of them passed. Against coupes & convertibles of a similar age (13.2% fail rate), the 2014 SLK comes out 1.5pp worse. Failures cluster in tyres, suspension and lighting & signalling.
What the MOT record shows
No single area dominates — tyres (6.7%) and suspension (6.5%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are coil spring, tread depth and headlamp aim — coil spring alone was recorded 1,164 times.
Mileage is the strongest signal on the record: 7.7% of 0-30k cars fail, rising to 20.0% once past 150k — 2.6× the risk.
Split by fuel, diesel examples fail 3.3pp more often than petrol ones (15.7% vs 12.4%) — worth weighing if you have a choice.
Advisories point at the next bill rather than this one: tyres was flagged on 24.4% of tests without failing them.
The trend is worsening — 11.8% of tests failed in 2021 against 17.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.7% | 1,906 |
| 2 | Suspension | 6.5% | 1,837 |
| 3 | Lighting & signalling | 2.6% | 739 |
| 4 | Brakes | 2.1% | 602 |
| 5 | Visibility | 1.3% | 368 |
| 6 | Emissions & environmental | 0.5% | 130 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Coil spring | 1,164 |
| 2 | Tread depth | 915 |
| 3 | Headlamp aim | 524 |
| 4 | Linkage ball joint dust cover | 405 |
| 5 | Ball joint dust cover | 299 |
| 6 | Washers | 251 |
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 | 24.4% | 6,889 |
| 2 | Brakes | 14.2% | 4,018 |
| 3 | Suspension | 10.7% | 3,015 |
| 4 | Other defects | 3.2% | 906 |
| 5 | Visibility | 2.5% | 704 |
| 6 | Road wheels | 1.9% | 545 |
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 | 4,787 | 7.7% |
| 30-60k | 14,741 | 13.9% |
| 60-90k | 7,013 | 19.3% |
| 90-120k | 1,471 | 22.4% |
| 120-150k | 234 | 30.3% |
| 150k+ | 30 | 20.0% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 19,868 | 15.7% |
| Petrol | 8,413 | 12.4% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 5,607 | 11.8% |
| 2022 | 5,544 | 12.8% |
| 2023 | 5,730 | 15.0% |
| 2024 | 5,669 | 16.4% |
| 2025 | 5,731 | 17.6% |
What to check before buying a 2014 SLK
On a 2014 SLK, tyres is what the MOT record says goes wrong most — it appeared in 6.7% of tests. Check these areas before you commit.
- Tyres (6.7% 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.
- Suspension (6.5% 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.
- Lighting & signalling (2.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
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 2014 Mercedes-Benz SLKs pass their MOT?
85.2% of the 28,281 2014 Mercedes-Benz SLK MOT tests in this dataset passed — a 14.8% fail rate.
What is the most common MOT failure on a 2014 Mercedes-Benz SLK?
Tyres, recorded in 6.7% of tests, followed by suspension (6.5%).
Does the 2014 SLK get worse with mileage?
Its MOT fail rate rises from 7.7% in the 0-30k band to 20.0% in the 150k+ band.
Methodology & source. Based on 28,281 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.