In 2025, 54,114 Mercedes-Benz Slk cars had a regular MOT in Great Britain. 72% passed first time, compared with 63% for all cars of the same ages, which makes the Slk better than average. Adjusted for age, it ranks 16 of the 217 most-tested car models.
That comparison matters: older cars fail more often, so a raw pass rate flatters models that are mostly young. We compare each model against every car on the road at the same age.
Pass rate by age
At 9 years old, 82% of Slks passed first time (all cars that age: 75%). By 20 years, that figure is 68% (all cars: 58%). It beats the average car at every age with enough data, from 9 to 20 years.
Mercedes-Benz Slk All cars of that age
| Age | Tests | Slk passed first time | All cars | Typical mileage |
|---|---|---|---|---|
| 9 years | 1,248 | 82% | 75% | 46,034 |
| 10 years | 4,846 | 80% | 72% | 51,810 |
| 11 years | 4,785 | 76% | 69% | 58,590 |
| 12 years | 4,483 | 74% | 66% | 65,842 |
| 13 years | 5,476 | 74% | 63% | 66,884 |
| 14 years | 2,482 | 75% | 61% | 63,568 |
| 15 years | 2,025 | 70% | 59% | 68,852 |
| 16 years | 2,446 | 69% | 58% | 71,423 |
| 17 years | 3,112 | 68% | 57% | 76,846 |
| 18 years | 3,379 | 67% | 57% | 77,682 |
| 19 years | 3,469 | 67% | 57% | 80,830 |
| 20 years | 4,416 | 68% | 58% | 82,190 |
What fails most on a Mercedes-Benz Slk
The area that lets the Slk down most, relative to other cars, is seat belts and airbags: 1.4% of tests failed on it, 4.3 times the rate for the average car. It does comparatively well on body and structure and lights and electrics.
Share of Slk tests failing on this area Average car
The six most common failure items
| Failure item | Area | Share of tests |
|---|---|---|
| A spring or spring component fractured or seriously weakened | Suspension | 5.7% |
| A suspension pin, bush or joint excessively worn | Suspension | 5.4% |
| The aim of a headlamp is not within limits laid down in the requirements | Lights and electrics | 3.8% |
| A tyre seriously damaged | Tyres | 3.3% |
| A suspension joint dust cover missing or no longer prevents the ingress of dirt etc | Suspension | 3.0% |
| Tyre tread depth not in accordance with the requirements | Tyres | 2.8% |
What to check when buying a used Slk
Based on where the Slk fails more often than other cars, these are the checks worth making before you buy:
- Seat belts and airbags: Pull every belt out fully and let it retract, check the buckles latch, and make sure the airbag light goes out after starting. More
- Suspension: Listen for knocks over speed bumps, look for leaking shock absorbers, and check the car sits level. Ask whether springs, bushes or drop links have been replaced. Repair guide
- Tyres: Check tread across the whole width (uneven wear hints at alignment or suspension faults), and look for cuts, bulges and mismatched brands. Repair guide
Then check the individual car: its own MOT history will show whether it follows the pattern. A car with repeated advisories in the same weak area is more likely to fail its next test.
Check a specific Slk
Enter the registration to see its full MOT history, mileage record and reliability score, compared with these figures.
Check a SlkFrequently asked questions
What is the MOT pass rate for a Mercedes-Benz Slk?
In 2025, 72% of Mercedes-Benz Slk cars passed their MOT first time, across 54,114 tests. Cars of the same ages averaged 63%.
What do Mercedes-Benz Slk cars most often fail their MOT on?
The most common failure items were: a spring or spring component fractured or seriously weakened (5.7% of tests); a suspension pin, bush or joint excessively worn (5.4% of tests); the aim of a headlamp is not within limits laid down in the requirements (3.8% of tests).
Other Mercedes-Benz models
Mercedes-Benz C-Class (74%), Mercedes-Benz A-Class (77%), Mercedes-Benz E-Class (77%), Mercedes-Benz Vito (67%), Mercedes-Benz B-Class (72%), Mercedes-Benz Glc (85%). All Mercedes-Benz models
Source: DVSA anonymised MOT tests and results, 2025 (class 4 normal tests; first-time pass means passed with no faults fixed at the test). Contains public sector information licensed under the Open Government Licence v3.0.