2,668 tests in 2025
Mercedes-Benz Cl reliability and MOT pass rate
81.7% passed first time. The 18.3% fail rate is 4.3 points better than the all-car average, on a median example 19 years old with 91,728 miles.
MOT pass rates / Mercedes-Benz
Pass rate
81.7%
22.6% of all cars failed; 18.3% of these did.
Fixed on the day
2.7%
Passed after a defect was put right during the visit.
Median at test
91,728 mi
19 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 13 | — |
| 6-9 years | 18 | — |
| 10-13 years | 270 | 20% |
| 14+ years | 2,366 | 18.1% |
What the Cl 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.
- Suspension12 dangerous39%
- Brakes84 dangerous37.2%
- Lamps, reflectors and electrical equipment29%
- Tyres118 dangerous20.9%
- Noise, emissions and leaks1 dangerous11.5%
- Visibility10.9%
- Seat belts and supplementary restraint systems7.8%
- Body, chassis, structure1 dangerous6.2%
Is the Cl getting worse?
The fail rate fell 1.2 points to 18.2% from 2022 to 2025, against a rising rate across all cars.
| Year | Tests | Median age | Fail rate | All cars | |
|---|---|---|---|---|---|
| 2022 | 3,542 | — | 19.4% | 22.5% | |
| 2023 | 3,379 | — | 19.5% | 22.8% | |
| 2024 | 2,715 | — | 19.2% | 23.2% | |
| 2025 | 2,663 | — | 18.2% | 22.6% |
Fail rate is first attempts at class 4 tests. Median age is the age of a typical Cl 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 Cl in 2025, counted by how many tests each one appeared on.
- 1Ball joint: ball joint excessively worn77 tests
- 2Position lamp: not working38 tests
- 3Rigid brake pipes: excessively corroded38 tests
- 4Condition: has ply or cords exposed37 tests
- 5Rbt (sp): efficiency below requirements36 tests
- 6Shock absorbers: has a serious fluid leak36 tests
- 7Tread depth: tread depth below requirements of 1.6mm36 tests
- 8SRS malfunction indicator lamp: warning lamp indicates a fault30 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical Cl collects 3.06 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.
- 1Rigid brake pipes: excessively corroded355 tests
- 2Tread depth: tread depth below requirements of 1.6mm319 tests
- 3Brake discs: in such a condition that it is seriously weakened249 tests
- 4Shock absorbers: has a serious fluid leak197 tests
- 5Engine oil leaks: leaking excessively from engine194 tests
- 6Ball joint: ball joint excessively worn147 tests
- 7Condition: has a tear, caused by separation or partial failure of its structure133 tests
- 8Brake pads: less than 1.5 mm thick131 tests
Questions
What is the Mercedes-Benz Cl MOT pass rate?
81.7% of the 2,668 Mercedes-Benz Cl first-attempt MOTs in 2025 passed. The fail rate of 18.3% compares with 22.6% across all cars. A further 2.7% passed after a defect was fixed during the test visit.
What does a Mercedes-Benz Cl usually fail on?
The single most common failure is "Ball joint: ball joint excessively worn", recorded on 77 failed tests, followed by "Position lamp: not working" and "Rigid brake pipes: excessively corroded". By section, suspension appears in 39% of failures, brakes appears in 37.2% of failures, lamps, reflectors and electrical equipment appears in 29% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was 15.4%; at 14+ years it was 18.1%. The median Mercedes-Benz Cl tested in 2025 was 19 years old with 91,728 miles.
Is the Mercedes-Benz Cl getting less reliable?
The fail rate fell 1.2 points to 18.2% from 2022 to 2025, against a rising rate across all cars.
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 Cl trim together. Year-on-year figures come from the same DVSA extracts for 2026 and earlier years. Full method on the pass rates hub.
Other Mercedes-Benz models
Checking a particular Cl?
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.