Mercedes-Benz SLC MOT pass rate & common failures
46,775 MOT tests on the Mercedes-Benz SLC (1980–2021) give it a 90.1% pass rate. Coupes & convertibles of a similar age fail at 9.8%, so the SLC sits squarely on the average. Its most common failure areas are tyres, suspension and lighting & signalling.
Best and worst SLC years
Ranked across SLC 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
Not every year is equal — 93.2% of 2019 examples pass against 88.7% of 2016 ones.
One area stands out: tyres, recorded in 6.0% of tests against 2.2% for the next-worst category.
At component level the recurring items are tread depth, headlamp aim and coil spring — tread depth alone was recorded 782 times.
Mileage is the strongest signal on the record: 7.0% of 0-30k cars fail, rising to 23.8% once past 120-150k — 3.4× the risk.
The petrol cars hold up better: 8.4% fail against 12.7% for diesel, a 4.3-point gap across 46,775 tests.
Tyres is the most common advisory, noted on 23.1% of tests — work that passed today but is likely due soon.
The trend is worsening — 7.9% of tests failed in 2021 against 11.7% in 2025, the usual pattern as a fleet ages.
How it compares
By model year
Every SLC model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2016 | 12,699 | 88.7% | 11.3% | Tyres |
| 2017 | 19,242 | 89.2% | 10.8% | Tyres |
| 2018 | 8,161 | 92.2% | 7.8% | Tyres |
| 2019 | 4,300 | 93.2% | 6.8% | Tyres |
| 2020 | 1,915 | 93.0% | 7.0% | Tyres |
| 2021 | 414 | 93.5% | 6.5% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.0% | 2,801 |
| 2 | Suspension | 2.2% | 1,035 |
| 3 | Lighting & signalling | 1.6% | 750 |
| 4 | Brakes | 1.0% | 471 |
| 5 | Emissions & environmental | 1.0% | 450 |
| 6 | Visibility | 0.6% | 267 |
| 7 | Road wheels | 0.5% | 222 |
| 8 | Other defects | 0.3% | 145 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Tread depth | 782 |
| 2 | Headlamp aim | 658 |
| 3 | Coil spring | 477 |
| 4 | Ball joint | 354 |
| 5 | Malfunction indicator lamp | 278 |
| 6 | Ball joint dust cover | 269 |
| 7 | Registration plates | 226 |
| 8 | Brake pads | 193 |
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 | 23.1% | 10,786 |
| 2 | Brakes | 5.3% | 2,488 |
| 3 | Suspension | 4.2% | 1,945 |
| 4 | Other defects | 2.9% | 1,331 |
| 5 | Visibility | 1.8% | 862 |
| 6 | Road wheels | 1.5% | 722 |
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 | 27,441 | 7.0% |
| 30-60k | 16,245 | 13.2% |
| 60-90k | 2,662 | 16.9% |
| 90-120k | 362 | 23.5% |
| 120-150k | 42 | 23.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 30,613 | 8.4% |
| Diesel | 16,162 | 12.7% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 8,030 | 7.9% |
| 2022 | 9,116 | 8.5% |
| 2023 | 9,784 | 9.9% |
| 2024 | 9,815 | 10.9% |
| 2025 | 10,030 | 11.7% |
What to check before buying a Mercedes-Benz SLC
- Tyres (6.0% 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 (2.2% 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.
- Lighting & signalling (1.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
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 SLC?
90.1% of the 46,775 Mercedes-Benz SLC MOT tests in this dataset passed, a 9.9% fail rate, across model years 1980–2021.
What does the Mercedes-Benz SLC most often fail its MOT on?
Tyres, recorded in 6.0% of tests, then suspension (2.2%).
Which SLC years are best and worst for MOT results?
2019 has the best pass rate at 93.2% and 2016 the weakest at 88.7%, from 4,300 and 12,699 tests respectively.
How much does mileage affect SLC MOT results?
Fail rates run at 7.0% for cars in the 0-30k band and 23.8% for 120-150k, a 16.8-point difference.
Is the petrol or diesel SLC more reliable at MOT time?
On MOT-testable defects the petrol fails 8.4% of the time against 12.7% for the diesel. This covers testable items only, not engine or gearbox reliability.
Methodology & source. Based on 46,775 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.