2012 Mercedes-Benz SLK — MOT failures & pass rate
33,408 MOT tests on the 2012 Mercedes-Benz SLK are in this dataset, and 82.3% of them passed. Against coupes & convertibles of a similar age (16.3% fail rate), the 2012 SLK comes out 1.4pp worse. Failures cluster in suspension, tyres and brakes.
What the MOT record shows
No single area dominates — suspension (8.6%) and tyres (6.0%) 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 rigid brake pipes — coil spring alone was recorded 1,281 times.
Condition tracks the odometer closely. Failures run at 8.8% in the 0-30k band and 22.7% in the 150k+ band, a 13.9-point spread — more than double.
Split by fuel, diesel examples fail 2.8pp more often than petrol ones (19.3% vs 16.4%) — 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 — 15.2% of tests failed in 2021 against 19.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 8.6% | 2,879 |
| 2 | Tyres | 6.0% | 2,006 |
| 3 | Brakes | 4.1% | 1,357 |
| 4 | Lighting & signalling | 3.8% | 1,284 |
| 5 | Visibility | 1.3% | 433 |
| 6 | Emissions & environmental | 0.9% | 287 |
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 | 1,281 |
| 2 | Tread depth | 989 |
| 3 | Rigid brake pipes | 866 |
| 4 | Ball joint dust cover | 807 |
| 5 | Linkage ball joint dust cover | 798 |
| 6 | Headlamp aim | 704 |
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% | 8,149 |
| 2 | Brakes | 23.0% | 7,697 |
| 3 | Suspension | 14.2% | 4,730 |
| 4 | Other defects | 3.4% | 1,123 |
| 5 | Visibility | 2.9% | 960 |
| 6 | Emissions & environmental | 2.7% | 898 |
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 | 3,048 | 8.8% |
| 30-60k | 14,979 | 15.0% |
| 60-90k | 11,168 | 20.8% |
| 90-120k | 3,419 | 25.4% |
| 120-150k | 660 | 25.0% |
| 150k+ | 132 | 22.7% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 18,883 | 16.4% |
| Diesel | 14,525 | 19.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 6,636 | 15.2% |
| 2022 | 6,703 | 16.8% |
| 2023 | 6,673 | 17.4% |
| 2024 | 6,714 | 19.3% |
| 2025 | 6,682 | 19.6% |
What to check before buying a 2012 SLK
On a 2012 SLK, suspension is what the MOT record says goes wrong most — it appeared in 8.6% of tests. Check these areas before you commit.
- Suspension (8.6% 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.
- Tyres (6.0% 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.
- Brakes (4.1% 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 2012 Mercedes-Benz SLKs pass their MOT?
82.3% of the 33,408 2012 Mercedes-Benz SLK MOT tests in this dataset passed — a 17.7% fail rate.
What is the most common MOT failure on a 2012 Mercedes-Benz SLK?
Suspension, recorded in 8.6% of tests, followed by tyres (6.0%).
Does the 2012 SLK get worse with mileage?
Its MOT fail rate rises from 8.8% in the 0-30k band to 22.7% in the 150k+ band.
Methodology & source. Based on 33,408 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.