1987 Mercedes-Benz Sl — MOT failures & pass rate
Across 627 MOT tests, the 1987 Mercedes-Benz Sl recorded an 85.8% pass rate. That is 2.2 percentage points better than coupes & convertibles of a similar age, which fail at 16.4%. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 7.8% of tests against 4.2% for the next-worst category.
At component level the recurring items are headlamp aim, washers and non catalyst emissions — headlamp aim alone was recorded 20 times.
Mileage is the strongest signal on the record: 6.5% of 0-30k cars fail, rising to 19.2% once past 120-150k — 2.9× the risk.
Suspension is the most common advisory, noted on 16.8% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 7.8% | 49 |
| 2 | Suspension | 4.2% | 26 |
| 3 | Brakes | 4.0% | 25 |
| 4 | Visibility | 3.5% | 22 |
| 5 | Emissions & environmental | 3.4% | 21 |
| 6 | Body, structure & corrosion | 2.5% | 16 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 20 |
| 2 | Washers | 17 |
| 3 | Non catalyst emissions | 16 |
| 4 | Ball joint dust cover | 16 |
| 5 | Service brake performance | 16 |
| 6 | Wipers | 13 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Suspension | 16.8% | 105 |
| 2 | Emissions & environmental | 16.3% | 102 |
| 3 | Brakes | 13.9% | 87 |
| 4 | Tyres | 9.7% | 61 |
| 5 | Steering | 8.9% | 56 |
| 6 | Body, structure & corrosion | 6.4% | 40 |
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 | 46 | 6.5% |
| 30-60k | 88 | 8.0% |
| 60-90k | 188 | 12.2% |
| 90-120k | 206 | 18.4% |
| 120-150k | 78 | 19.2% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 118 | 13.6% |
| 2022 | 134 | 14.9% |
| 2023 | 133 | 18.1% |
| 2024 | 120 | 11.7% |
| 2025 | 122 | 12.3% |
What to check before buying a 1987 Sl
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 7.8% of tests. Start there.
- Lighting & signalling (7.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (4.2% 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 (4.0% 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 1987 Mercedes-Benz Sls pass their MOT?
85.8% of the 627 1987 Mercedes-Benz Sl MOT tests in this dataset passed — a 14.2% fail rate.
What is the most common MOT failure on a 1987 Mercedes-Benz Sl?
Lighting & signalling, recorded in 7.8% of tests, followed by suspension (4.2%).
Does the 1987 Sl get worse with mileage?
Its MOT fail rate rises from 6.5% in the 0-30k band to 19.2% in the 120-150k band.
Methodology & source. Based on 627 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.