1988 Mercedes-Benz Sl — MOT failures & pass rate
Across 767 MOT tests, the 1988 Mercedes-Benz Sl recorded an 88.0% pass rate. Coupes & convertibles of a similar age fail 16.9% of the time, so this is 4.9pp better than the group it competes with. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
No single area dominates — lighting & signalling (7.0%) and suspension (4.7%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, ball joint dust cover and washers — headlamp aim alone was recorded 48 times.
Mileage matters less than usual here: the 1988 Sl fails 10.0% of the time in the 0-30k band and 13.9% at 150k+, a spread of only 3.9 points.
Advisories point at the next bill rather than this one: suspension was flagged on 16.7% of tests without failing them.
The trend is worsening — 9.3% of tests failed in 2021 against 11.9% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 7.0% | 54 |
| 2 | Suspension | 4.7% | 36 |
| 3 | Brakes | 3.6% | 28 |
| 4 | Emissions & environmental | 3.1% | 24 |
| 5 | Visibility | 3.0% | 23 |
| 6 | Body, structure & corrosion | 1.8% | 14 |
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 | 48 |
| 2 | Ball joint dust cover | 25 |
| 3 | Washers | 22 |
| 4 | Component mounting prescribed areas | 17 |
| 5 | Service brake performance | 16 |
| 6 | Non catalyst emissions | 16 |
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 | 16.7% | 128 |
| 2 | Brakes | 12.1% | 93 |
| 3 | Emissions & environmental | 11.9% | 91 |
| 4 | Tyres | 9.8% | 75 |
| 5 | Body, structure & corrosion | 7.2% | 55 |
| 6 | Steering | 6.4% | 49 |
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 | 50 | 10.0% |
| 30-60k | 181 | 9.9% |
| 60-90k | 231 | 11.3% |
| 90-120k | 199 | 14.1% |
| 120-150k | 70 | 14.3% |
| 150k+ | 36 | 13.9% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 150 | 9.3% |
| 2022 | 166 | 11.5% |
| 2023 | 155 | 13.6% |
| 2024 | 153 | 13.7% |
| 2025 | 143 | 11.9% |
What to check before buying a 1988 Sl
On a 1988 Sl, lighting & signalling is what the MOT record says goes wrong most — it appeared in 7.0% of tests. Check these areas before you commit.
- Lighting & signalling (7.0% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (4.7% 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 (3.6% 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 1988 Mercedes-Benz Sls pass their MOT?
88.0% of the 767 1988 Mercedes-Benz Sl MOT tests in this dataset passed — a 12.0% fail rate.
What is the most common MOT failure on a 1988 Mercedes-Benz Sl?
Lighting & signalling, recorded in 7.0% of tests, followed by suspension (4.7%).
Does the 1988 Sl get worse with mileage?
Its MOT fail rate rises from 10.0% in the 0-30k band to 13.9% in the 150k+ band.
Methodology & source. Based on 767 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.