2003 Mercedes-Benz Sl — MOT failures & pass rate
The 2003 Mercedes-Benz Sl passed 84.8% of its 14,138 recorded MOT tests. Against coupes & convertibles of a similar age (22.6% fail rate), the 2003 Sl comes out 7.4pp better. Failures cluster in suspension, lighting & signalling and brakes.
What the MOT record shows
No single area dominates — suspension (5.8%) and lighting & signalling (4.6%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are ball joint, shock absorbers and rigid brake pipes — ball joint alone was recorded 401 times.
Mileage is the strongest signal on the record: 8.8% of 0-30k cars fail, rising to 23.3% once past 150k — 2.6× the risk.
Brakes is the most common advisory, noted on 23.6% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 5.8% | 815 |
| 2 | Lighting & signalling | 4.6% | 649 |
| 3 | Brakes | 4.5% | 635 |
| 4 | Tyres | 3.6% | 515 |
| 5 | Visibility | 2.0% | 286 |
| 6 | Seat belts & restraints | 1.8% | 256 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Ball joint | 401 |
| 2 | Shock absorbers | 287 |
| 3 | Rigid brake pipes | 271 |
| 4 | SRS malfunction indicator lamp | 246 |
| 5 | Ball joint dust cover | 237 |
| 6 | Headlamp aim | 224 |
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 | 23.6% | 3,337 |
| 2 | Suspension | 20.9% | 2,956 |
| 3 | Tyres | 18.7% | 2,649 |
| 4 | Other defects | 6.2% | 876 |
| 5 | Emissions & environmental | 5.6% | 786 |
| 6 | Lighting & signalling | 4.9% | 688 |
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 | 893 | 8.8% |
| 30-60k | 3,656 | 11.5% |
| 60-90k | 5,269 | 15.6% |
| 90-120k | 3,052 | 18.0% |
| 120-150k | 899 | 20.2% |
| 150k+ | 313 | 23.3% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,127 | 15.6% |
| 2022 | 3,025 | 15.8% |
| 2023 | 2,818 | 14.4% |
| 2024 | 2,665 | 15.5% |
| 2025 | 2,503 | 14.4% |
What to check before buying a 2003 Sl
The failure pattern for this year is specific enough to inspect against: suspension accounted for 5.8% of tests. Start there.
- Suspension (5.8% 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 (4.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (4.5% 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 2003 Mercedes-Benz Sls pass their MOT?
84.8% of the 14,138 2003 Mercedes-Benz Sl MOT tests in this dataset passed — a 15.2% fail rate.
What is the most common MOT failure on a 2003 Mercedes-Benz Sl?
Suspension, recorded in 5.8% of tests, followed by lighting & signalling (4.6%).
Does the 2003 Sl get worse with mileage?
Its MOT fail rate rises from 8.8% in the 0-30k band to 23.3% in the 150k+ band.
Methodology & source. Based on 14,138 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.