2017 Mercedes-Benz SLC — MOT failures & pass rate
Across 19,242 MOT tests, the 2017 Mercedes-Benz SLC recorded an 89.2% pass rate. That is effectively the same as coupes & convertibles of a similar age (9.8% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in tyres, suspension and lighting & signalling.
What the MOT record shows
One area stands out: tyres, recorded in 6.3% of tests against 3.0% for the next-worst category.
At component level the recurring items are tread depth, ball joint and headlamp aim — tread depth alone was recorded 347 times.
A 90-120k example is materially riskier than a 0-30k one: 26.8% versus 7.8%.
The petrol cars hold up better: 9.3% fail against 12.6% for diesel, a 3.3-point gap across 19,242 tests.
Tyres is the most common advisory, noted on 23.3% of tests — work that passed today but is likely due soon.
The trend is worsening — 7.8% of tests failed in 2021 against 13.8% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 6.3% | 1,216 |
| 2 | Suspension | 3.0% | 577 |
| 3 | Lighting & signalling | 1.5% | 288 |
| 4 | Brakes | 1.1% | 211 |
| 5 | Emissions & environmental | 1.1% | 209 |
| 6 | Road wheels | 0.5% | 104 |
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 | 347 |
| 2 | Ball joint | 268 |
| 3 | Headlamp aim | 254 |
| 4 | Coil spring | 195 |
| 5 | Ball joint dust cover | 191 |
| 6 | Malfunction indicator lamp | 137 |
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 | 23.3% | 4,492 |
| 2 | Brakes | 5.6% | 1,081 |
| 3 | Suspension | 4.4% | 841 |
| 4 | Other defects | 3.0% | 569 |
| 5 | Visibility | 1.9% | 366 |
| 6 | Road wheels | 1.4% | 273 |
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 | 10,602 | 7.8% |
| 30-60k | 7,353 | 13.9% |
| 60-90k | 1,136 | 17.0% |
| 90-120k | 127 | 26.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 10,434 | 9.3% |
| Diesel | 8,808 | 12.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,794 | 7.8% |
| 2022 | 3,816 | 9.2% |
| 2023 | 3,874 | 11.3% |
| 2024 | 3,834 | 11.9% |
| 2025 | 3,924 | 13.8% |
What to check before buying a 2017 SLC
The failure pattern for this year is specific enough to inspect against: tyres accounted for 6.3% of tests. Start there.
- Tyres (6.3% 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 (3.0% 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 (1.5% 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
How many 2017 Mercedes-Benz SLCs pass their MOT?
89.2% of the 19,242 2017 Mercedes-Benz SLC MOT tests in this dataset passed — a 10.8% fail rate.
What is the most common MOT failure on a 2017 Mercedes-Benz SLC?
Tyres, recorded in 6.3% of tests, followed by suspension (3.0%).
Does the 2017 SLC get worse with mileage?
Its MOT fail rate rises from 7.8% in the 0-30k band to 26.8% in the 90-120k band.
Methodology & source. Based on 19,242 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.