2009 Mercedes-Benz SLK — MOT failures & pass rate
15,586 MOT tests on the 2009 Mercedes-Benz SLK are in this dataset, and 78.3% of them passed. That is 1.4 percentage points worse than coupes & convertibles of a similar age, which fail at 20.3%. Failures cluster in suspension, brakes and lighting & signalling.
What the MOT record shows
Suspension dominates the failure mix at 12.1% of all tests — 5.9 points clear of brakes, so it is the first thing to check.
At component level the recurring items are coil spring, ball joint and rigid brake pipes — coil spring alone was recorded 1,198 times.
A 150k+ example is materially riskier than a 0-30k one: 25.4% versus 11.3%.
Advisories point at the next bill rather than this one: brakes was flagged on 26.4% of tests without failing them.
The trend is worsening — 20.8% of tests failed in 2021 against 22.3% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 12.1% | 1,892 |
| 2 | Brakes | 6.3% | 978 |
| 3 | Lighting & signalling | 6.1% | 957 |
| 4 | Tyres | 4.7% | 726 |
| 5 | Visibility | 2.8% | 431 |
| 6 | Emissions & environmental | 1.5% | 236 |
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 | 1,198 |
| 2 | Ball joint | 769 |
| 3 | Rigid brake pipes | 576 |
| 4 | Tread depth | 363 |
| 5 | Rbt (sp) | 344 |
| 6 | Washers | 292 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 26.4% | 4,119 |
| 2 | Tyres | 24.2% | 3,767 |
| 3 | Suspension | 18.3% | 2,853 |
| 4 | Lighting & signalling | 7.6% | 1,178 |
| 5 | Body, structure & corrosion | 5.9% | 928 |
| 6 | Other defects | 5.5% | 853 |
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 | 1,072 | 11.3% |
| 30-60k | 5,598 | 18.2% |
| 60-90k | 6,008 | 23.8% |
| 90-120k | 2,212 | 28.3% |
| 120-150k | 575 | 28.0% |
| 150k+ | 114 | 25.4% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,183 | 20.8% |
| 2022 | 3,155 | 20.9% |
| 2023 | 3,168 | 23.1% |
| 2024 | 3,050 | 21.6% |
| 2025 | 3,030 | 22.3% |
What to check before buying a 2009 SLK
On a 2009 SLK, suspension is what the MOT record says goes wrong most — it appeared in 12.1% of tests. Check these areas before you commit.
- Suspension (12.1% 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.
- Brakes (6.3% 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.
- Lighting & signalling (6.1% 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 2009 Mercedes-Benz SLKs pass their MOT?
78.3% of the 15,586 2009 Mercedes-Benz SLK MOT tests in this dataset passed — a 21.7% fail rate.
What is the most common MOT failure on a 2009 Mercedes-Benz SLK?
Suspension, recorded in 12.1% of tests, followed by brakes (6.3%).
Does the 2009 SLK get worse with mileage?
Its MOT fail rate rises from 11.3% in the 0-30k band to 25.4% in the 150k+ band.
Methodology & source. Based on 15,586 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.