Mercedes-Benz Sl MOT pass rate & common failures
Across 44 model years and 121,123 tests, the Mercedes-Benz Sl passes its MOT 86.9% of the time. Against coupes & convertibles of a similar age (19.0% fail rate), the Sl comes out 5.8pp better. Its most common failure areas are lighting & signalling, suspension and tyres.
Best and worst Sl years
Ranked across Sl years with at least 1,000 tests. Older cars fail more simply because they are older — compare years close together in age before drawing conclusions.
What the MOT record shows
The strongest year on this record is 2019 (93.9% pass rate); the weakest is 2002 (84.7%). Older cars carry more of the difference than the average implies.
No single area dominates — lighting & signalling (4.6%) and suspension (4.4%) 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 and rigid brake pipes — headlamp aim alone was recorded 2,521 times.
Mileage is the strongest signal on the record: 6.8% of 0-30k cars fail, rising to 20.9% once past 150k — 3.1× the risk.
Advisories point at the next bill rather than this one: brakes was flagged on 18.9% of tests without failing them.
How it compares
By model year
Every Sl model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 1980 | 178 | 82.0% | 18.0% | Lighting & signalling |
| 1981 | 173 | 87.9% | 12.1% | Lighting & signalling |
| 1982 | 234 | 82.9% | 17.1% | Lighting & signalling |
| 1983 | 576 | 85.9% | 14.1% | Lighting & signalling |
| 1984 | 798 | 83.0% | 17.0% | Lighting & signalling |
| 1985 | 1,033 | 84.8% | 15.2% | Lighting & signalling |
| 1986 | 791 | 84.1% | 15.9% | Lighting & signalling |
| 1987 | 627 | 85.8% | 14.2% | Lighting & signalling |
| 1988 | 767 | 88.0% | 12.0% | Lighting & signalling |
| 1989 | 877 | 85.3% | 14.7% | Lighting & signalling |
| 1990 | 430 | 86.1% | 14.0% | Lighting & signalling |
| 1991 | 667 | 87.6% | 12.4% | Lighting & signalling |
| 1992 | 692 | 88.9% | 11.1% | Lighting & signalling |
| 1993 | 940 | 86.4% | 13.6% | Lighting & signalling |
| 1994 | 2,335 | 85.0% | 14.9% | Lighting & signalling |
| 1995 | 3,145 | 85.0% | 15.0% | Lighting & signalling |
| 1996 | 3,304 | 87.1% | 12.9% | Lighting & signalling |
| 1997 | 3,843 | 86.7% | 13.3% | Lighting & signalling |
| 1998 | 4,031 | 85.9% | 14.1% | Lighting & signalling |
| 1999 | 3,177 | 87.3% | 12.7% | Lighting & signalling |
| 2000 | 2,836 | 86.3% | 13.8% | Lighting & signalling |
| 2001 | 1,614 | 87.7% | 12.3% | Lighting & signalling |
| 2002 | 5,831 | 84.7% | 15.3% | Suspension |
| 2003 | 14,138 | 84.8% | 15.2% | Suspension |
| 2004 | 10,904 | 86.0% | 14.0% | Suspension |
| 2005 | 6,634 | 86.1% | 13.9% | Suspension |
| 2006 | 4,722 | 85.4% | 14.6% | Suspension |
| 2007 | 4,579 | 85.8% | 14.2% | Suspension |
| 2008 | 4,453 | 86.4% | 13.6% | Suspension |
| 2009 | 2,808 | 85.3% | 14.7% | Suspension |
| 2010 | 2,071 | 85.7% | 14.3% | Tyres |
| 2011 | 1,470 | 88.7% | 11.3% | Tyres |
| 2012 | 2,354 | 86.6% | 13.4% | Tyres |
| 2013 | 6,343 | 87.1% | 12.9% | Tyres |
| 2014 | 5,882 | 89.5% | 10.5% | Tyres |
| 2015 | 4,405 | 90.7% | 9.3% | Tyres |
| 2016 | 4,257 | 91.2% | 8.8% | Tyres |
| 2017 | 3,458 | 92.7% | 7.3% | Tyres |
| 2018 | 2,205 | 93.1% | 6.9% | Tyres |
| 2019 | 1,488 | 93.9% | 6.1% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 4.6% | 5,616 |
| 2 | Suspension | 4.4% | 5,312 |
| 3 | Tyres | 3.8% | 4,578 |
| 4 | Brakes | 3.2% | 3,924 |
| 5 | Visibility | 2.0% | 2,460 |
| 6 | Emissions & environmental | 1.8% | 2,164 |
| 7 | Body, structure & corrosion | 0.8% | 1,004 |
| 8 | Seat belts & restraints | 0.7% | 830 |
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 | 2,521 |
| 2 | Ball joint | 1,912 |
| 3 | Rigid brake pipes | 1,613 |
| 4 | Ball joint dust cover | 1,494 |
| 5 | Coil spring | 1,479 |
| 6 | Wipers | 1,419 |
| 7 | Catalyst emissions | 1,310 |
| 8 | Washers | 1,200 |
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 | 18.9% | 22,864 |
| 2 | Tyres | 17.2% | 20,825 |
| 3 | Suspension | 14.4% | 17,483 |
| 4 | Emissions & environmental | 6.3% | 7,615 |
| 5 | Other defects | 4.3% | 5,234 |
| 6 | Lighting & signalling | 4.2% | 5,054 |
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 | 18,719 | 6.8% |
| 30-60k | 36,229 | 10.9% |
| 60-90k | 34,528 | 14.6% |
| 90-120k | 20,559 | 16.8% |
| 120-150k | 7,776 | 18.5% |
| 150k+ | 3,129 | 20.9% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 120,978 | 13.1% |
| Diesel | 141 | 22.7% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 25,629 | 13.2% |
| 2022 | 25,417 | 13.1% |
| 2023 | 24,439 | 13.0% |
| 2024 | 23,093 | 13.2% |
| 2025 | 22,545 | 13.3% |
What to check before buying a Mercedes-Benz Sl
- 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.
- Suspension (4.4% 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.
- Tyres (3.8% 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.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the Mercedes-Benz Sl?
86.9% of the 121,123 Mercedes-Benz Sl MOT tests in this dataset passed, a 13.1% fail rate, across model years 1980–2023.
What does the Mercedes-Benz Sl most often fail its MOT on?
Lighting & signalling, recorded in 4.6% of tests, then suspension (4.4%).
Which Sl years are best and worst for MOT results?
2019 has the best pass rate at 93.9% and 2002 the weakest at 84.7%, from 1,488 and 5,831 tests respectively.
How much does mileage affect Sl MOT results?
Fail rates run at 6.8% for cars in the 0-30k band and 20.9% for 150k+, a 14.1-point difference.
Methodology & source. Based on 121,123 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.