2012 Mercedes-Benz Sl — MOT failures & pass rate
Across 2,354 MOT tests, the 2012 Mercedes-Benz Sl recorded an 86.6% pass rate. Against coupes & convertibles of a similar age (16.2% fail rate), the 2012 Sl comes out 2.8pp better. Failures cluster in tyres, suspension and emissions & environmental.
What the MOT record shows
One area stands out: tyres, recorded in 6.0% of tests against 3.0% for the next-worst category.
At component level the recurring items are malfunction indicator lamp, ball joint and headlamp aim — malfunction indicator lamp alone was recorded 59 times.
Condition tracks the odometer closely. Failures run at 8.2% in the 0-30k band and 13.0% in the 90-120k band, a 4.8-point spread.
Tyres is the most common advisory, noted on 19.3% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.0% | 142 |
| 2 | Suspension | 3.0% | 70 |
| 3 | Emissions & environmental | 2.8% | 66 |
| 4 | Brakes | 2.5% | 59 |
| 5 | Lighting & signalling | 2.3% | 53 |
| 6 | Visibility | 1.2% | 29 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Malfunction indicator lamp | 59 |
| 2 | Ball joint | 33 |
| 3 | Headlamp aim | 27 |
| 4 | Rigid brake pipes | 24 |
| 5 | Coil spring | 20 |
| 6 | Anti-lock braking system | 17 |
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 | 19.3% | 455 |
| 2 | Brakes | 11.7% | 275 |
| 3 | Suspension | 5.8% | 137 |
| 4 | Other defects | 3.1% | 74 |
| 5 | Road wheels | 2.5% | 58 |
| 6 | Lighting & signalling | 2.0% | 47 |
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 | 589 | 8.2% |
| 30-60k | 1,212 | 13.6% |
| 60-90k | 426 | 19.5% |
| 90-120k | 108 | 13.0% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 490 | 13.3% |
| 2022 | 462 | 11.9% |
| 2023 | 489 | 15.5% |
| 2024 | 460 | 12.6% |
| 2025 | 453 | 13.5% |
What to check before buying a 2012 Sl
The failure pattern for this year is specific enough to inspect against: tyres accounted for 6.0% of tests. Start there.
- 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.
- Suspension (3.0% 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.
- Emissions & environmental (2.8% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
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 Sls pass their MOT?
86.6% of the 2,354 2012 Mercedes-Benz Sl MOT tests in this dataset passed — a 13.4% fail rate.
What is the most common MOT failure on a 2012 Mercedes-Benz Sl?
Tyres, recorded in 6.0% of tests, followed by suspension (3.0%).
Does the 2012 Sl get worse with mileage?
Its MOT fail rate rises from 8.2% in the 0-30k band to 13.0% in the 90-120k band.
Methodology & source. Based on 2,354 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.