8,174 tests in 2025
Mercedes-Benz Slc reliability and MOT pass rate
86.8% passed first time. The 13.2% fail rate is 9.4 points better than the all-car average, on a median example 8 years old with 33,360 miles.
MOT pass rates / Mercedes-Benz
Pass rate
86.8%
22.6% of all cars failed; 13.2% of these did.
Fixed on the day
1.7%
Passed after a defect was put right during the visit.
Median at test
33,360 mi
8 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 703 | 7.8% |
| 6-9 years | 7,469 | 13.7% |
| 10-13 years | 2 | — |
| 14+ years | 0 | — |
What the Slc fails on
Share of failed tests with at least one fail item in each DVSA inspection section. A test can fail in several sections at once.
- Tyres505 dangerous46%
- Suspension6 dangerous36.3%
- Brakes34 dangerous11.2%
- Noise, emissions and leaks9.8%
- Lamps, reflectors and electrical equipment6%
- Road Wheels49 dangerous5.4%
- Visibility3%
- Identification of the vehicle2%
Is the Slc getting worse?
The fail rate rose 4.4 points to 13.6% from 2022 to 2025 while the median one tested aged 3 years. Ageing alone would predict about 6.6 points, so it is holding up better than the fleet average for its age.
| Year | Tests | Median age | Fail rate | All cars | |
|---|---|---|---|---|---|
| 2022 | 8,348 | 5 | 9.2% | 22.5% | |
| 2023 | 8,321 | 6 | 11.2% | 22.8% | |
| 2024 | 6,947 | 7 | 12.2% | 23.2% | |
| 2025 | 7,561 | 8 | 13.6% | 22.6% |
Fail rate is first attempts at class 4 tests. Median age is the age of a typical Slc at its test that year, and it is the number to watch: across the whole fleet each extra year of age adds roughly 1.9 points to the fail rate, so a model whose age and fail rate rise together is simply getting older.
The exact defects that fail it
Every failure item DVSA recorded against a Slc in 2025, counted by how many tests each one appeared on.
- 1Condition: has ply or cords exposed181 tests
- 2Coil spring: fractured or broken161 tests
- 3Condition: has a cut in excess of the requirements deep enough to reach the ply or cords155 tests
- 4Ball joint: ball joint excessively worn112 tests
- 5Tread depth: tread depth below requirements of 1.6mm101 tests
- 6Malfunction indicator lamp: inoperative or indicates a malfunction72 tests
- 7Ball joint dust cover: ball joint dust cover no longer prevents the ingress of dirt70 tests
- 8Anti-lock braking system: warning lamp indicates an ABS fault62 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical Slc collects 2.16 of them per test, and these are the ones that come up most. Treat it as the running-repairs list for the next year or two.
- 1Tread depth: tread depth below requirements of 1.6mm1,112 tests
- 2Condition: has a tear, caused by separation or partial failure of its structure576 tests
- 3Brake discs: in such a condition that it is seriously weakened300 tests
- 4Condition: has a cut in excess of the requirements deep enough to reach the ply or cords297 tests
- 5Wheel bearings: has excessive play220 tests
- 6Brake pads: less than 1.5 mm thick215 tests
- 7Tread depth: tread pattern not visible over the whole tread area when minimum depth required is 1.0mm172 tests
- 8Condition: has a bulge, caused by separation or partial failure of its structure162 tests
Questions
What is the Mercedes-Benz Slc MOT pass rate?
86.8% of the 8,174 Mercedes-Benz Slc first-attempt MOTs in 2025 passed. The fail rate of 13.2% compares with 22.6% across all cars. A further 1.7% passed after a defect was fixed during the test visit.
What does a Mercedes-Benz Slc usually fail on?
The single most common failure is "Condition: has ply or cords exposed", recorded on 181 failed tests, followed by "Coil spring: fractured or broken" and "Condition: has a cut in excess of the requirements deep enough to reach the ply or cords". By section, tyres appears in 46% of failures, suspension appears in 36.3% of failures, brakes appears in 11.2% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was 7.8%; at 6-9 years it was 13.7%. The median Mercedes-Benz Slc tested in 2025 was 8 years old with 33,360 miles.
Is the Mercedes-Benz Slc getting less reliable?
The fail rate rose 4.4 points to 13.6% from 2022 to 2025 while the median one tested aged 3 years. Ageing alone would predict about 6.6 points, so it is holding up better than the fleet average for its age.
First-attempt class 4 tests, 2025, from DVSA’s anonymised MOT data (OGL v3, retrieved 2026-09-12). DVSA records newer cars trim by trim; this page adds every Slc trim together. Year-on-year figures come from the same DVSA extracts for 2026 and earlier years. Full method on the pass rates hub.
DVSA has published 16 safety recalls naming the Mercedes-Benz Slc: Mercedes-Benz Slc recalls.
Other Mercedes-Benz models
Checking a particular Slc?
The odds above are the model. The car in front of you has its own record: every test, every advisory, the mileage at each one.
Due a test? Find an approved MOT station near you.