2015 Mercedes-Benz Sl — MOT failures & pass rate
Across 4,405 MOT tests, the 2015 Mercedes-Benz Sl recorded a 90.7% pass rate. Coupes & convertibles of a similar age fail 11.9% of the time, so this is 2.6pp better than the group it competes with. Failures cluster in tyres, suspension and lighting & signalling.
What the MOT record shows
Tyres dominates the failure mix at 5.7% of all tests — 3.8 points clear of suspension, so it is the first thing to check.
At component level the recurring items are coil spring, tread depth and registration plates — coil spring alone was recorded 58 times.
A 90-120k example is materially riskier than a 0-30k one: 19.1% versus 6.2%.
Advisories point at the next bill rather than this one: tyres was flagged on 17.6% of tests without failing them.
The trend is worsening — 7.5% of tests failed in 2021 against 11.2% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 5.7% | 251 |
| 2 | Suspension | 1.9% | 86 |
| 3 | Lighting & signalling | 1.1% | 47 |
| 4 | Visibility | 1.0% | 43 |
| 5 | Brakes | 0.6% | 28 |
| 6 | Other defects | 0.6% | 27 |
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 | 58 |
| 2 | Tread depth | 51 |
| 3 | Registration plates | 47 |
| 4 | Ball joint | 36 |
| 5 | Headlamp aim | 35 |
| 6 | Washers | 34 |
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 | 17.6% | 774 |
| 2 | Brakes | 6.7% | 295 |
| 3 | Suspension | 3.9% | 172 |
| 4 | Visibility | 2.8% | 121 |
| 5 | Other defects | 2.3% | 102 |
| 6 | Road wheels | 2.2% | 97 |
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 | 1,756 | 6.2% |
| 30-60k | 2,089 | 10.2% |
| 60-90k | 478 | 15.3% |
| 90-120k | 63 | 19.1% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 890 | 7.5% |
| 2022 | 879 | 8.1% |
| 2023 | 888 | 8.5% |
| 2024 | 897 | 11.4% |
| 2025 | 851 | 11.2% |
What to check before buying a 2015 Sl
On a 2015 Sl, tyres is what the MOT record says goes wrong most — it appeared in 5.7% of tests. Check these areas before you commit.
- Tyres (5.7% 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 (1.9% 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 (1.1% 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 2015 Mercedes-Benz Sls pass their MOT?
90.7% of the 4,405 2015 Mercedes-Benz Sl MOT tests in this dataset passed — a 9.3% fail rate.
What is the most common MOT failure on a 2015 Mercedes-Benz Sl?
Tyres, recorded in 5.7% of tests, followed by suspension (1.9%).
Does the 2015 Sl get worse with mileage?
Its MOT fail rate rises from 6.2% in the 0-30k band to 19.1% in the 90-120k band.
Methodology & source. Based on 4,405 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.