2014 Mercedes-Benz Sl — MOT failures & pass rate
The 2014 Mercedes-Benz Sl passed 89.5% of its 5,882 recorded MOT tests. That is 2.8 percentage points better than coupes & convertibles of a similar age, which fail at 13.2%. Failures cluster in tyres, suspension and emissions & environmental.
What the MOT record shows
One area stands out: tyres, recorded in 5.6% of tests against 2.1% for the next-worst category.
At component level the recurring items are malfunction indicator lamp, headlamp aim and ball joint — malfunction indicator lamp alone was recorded 94 times.
Condition tracks the odometer closely. Failures run at 6.1% in the 0-30k band and 19.2% in the 90-120k band, a 13.1-point spread — more than double.
Tyres is the most common advisory, noted on 17.7% of tests — work that passed today but is likely due soon.
The trend is worsening — 8.7% of tests failed in 2021 against 12.6% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 5.6% | 330 |
| 2 | Suspension | 2.1% | 126 |
| 3 | Emissions & environmental | 1.8% | 105 |
| 4 | Lighting & signalling | 1.7% | 100 |
| 5 | Brakes | 1.2% | 72 |
| 6 | Visibility | 1.0% | 57 |
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 | 94 |
| 2 | Headlamp aim | 64 |
| 3 | Ball joint | 60 |
| 4 | Rigid brake pipes | 57 |
| 5 | Washers | 49 |
| 6 | Coil spring | 47 |
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 | 17.7% | 1,043 |
| 2 | Brakes | 11.3% | 664 |
| 3 | Suspension | 3.9% | 230 |
| 4 | Other defects | 2.5% | 145 |
| 5 | Visibility | 2.1% | 124 |
| 6 | Road wheels | 1.7% | 101 |
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 | 1,596 | 6.1% |
| 30-60k | 3,077 | 10.3% |
| 60-90k | 1,001 | 16.1% |
| 90-120k | 177 | 19.2% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,187 | 8.7% |
| 2022 | 1,160 | 9.4% |
| 2023 | 1,183 | 10.8% |
| 2024 | 1,160 | 10.8% |
| 2025 | 1,192 | 12.6% |
What to check before buying a 2014 Sl
The failure pattern for this year is specific enough to inspect against: tyres accounted for 5.6% of tests. Start there.
- Tyres (5.6% 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 (2.1% 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.
- Emissions & environmental (1.8% 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 2014 Mercedes-Benz Sls pass their MOT?
89.5% of the 5,882 2014 Mercedes-Benz Sl MOT tests in this dataset passed — a 10.5% fail rate.
What is the most common MOT failure on a 2014 Mercedes-Benz Sl?
Tyres, recorded in 5.6% of tests, followed by suspension (2.1%).
Does the 2014 Sl get worse with mileage?
Its MOT fail rate rises from 6.1% in the 0-30k band to 19.2% in the 90-120k band.
Methodology & source. Based on 5,882 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.