20,473 tests in 2025
Smart (MCC) Forfour reliability and MOT pass rate
78% passed first time. The 22% fail rate is 0.6 points better than the all-car average, on a median example 9 years old with 44,336 miles.
Pass rate
78%
22.6% of all cars failed; 22% of these did.
Fixed on the day
5.7%
Passed after a defect was put right during the visit.
Median at test
44,336 mi
9 years old.
Fail rate by age
| Age at test | Tests | Fail rate |
|---|---|---|
| 3-5 years | 7 | — |
| 6-9 years | 14,427 | 19.4% |
| 10-13 years | 5,022 | 27.1% |
| 14+ years | 1,016 | 34.6% |
What the Forfour 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.
- Suspension64 dangerous33.9%
- Tyres1,549 dangerous33%
- Noise, emissions and leaks24.1%
- Lamps, reflectors and electrical equipment16 dangerous20.1%
- Visibility2 dangerous16.4%
- Brakes423 dangerous15.3%
- Body, chassis, structure22 dangerous10.7%
- Steering5 dangerous2.9%
Is the Forfour getting worse?
The fail rate rose 5.2 points to 22% from 2022 to 2025 while the median one tested aged 3 years. Ageing alone would predict about 7.5 points, so it is holding up better than the fleet average for its age.
| Year | Tests | Median age | Fail rate | All cars | |
|---|---|---|---|---|---|
| 2022 | 23,475 | 6 | 16.8% | 22.5% | |
| 2023 | 23,088 | 7 | 18.8% | 22.8% | |
| 2024 | 19,142 | 8 | 21.1% | 23.2% | |
| 2025 | 20,468 | 9 | 22% | 22.6% |
Fail rate is first attempts at class 4 tests. Median age is the age of a typical Forfour 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 Forfour in 2025, counted by how many tests each one appeared on.
- 1Ball joint: ball joint excessively worn688 tests
- 2Tread depth: tread depth below requirements of 1.6mm648 tests
- 3Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits607 tests
- 4Wipers: does not clear the windscreen effectively426 tests
- 5Coil spring: fractured or broken404 tests
- 6Stop lamp: not working369 tests
- 7Condition: has ply or cords exposed326 tests
- 8Exhaust system: has a major leak of exhaust gases321 tests
What wears out first
Advisories are the tester flagging wear that is still legal. A typical Forfour collects 2.23 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 1.6mm3,523 tests
- 2Brake discs: in such a condition that it is seriously weakened2,304 tests
- 3Condition: has a tear, caused by separation or partial failure of its structure1,997 tests
- 4Brake pads: less than 1.5 mm thick1,148 tests
- 5Brake discs: significantly and obviously worn855 tests
- 6Pins and bushes: pin or bush excessively worn626 tests
- 7Engine oil leaks: leaking excessively from engine503 tests
- 8Tread depth: tread pattern not visible over the whole tread area when minimum depth required is 1.0mm499 tests
Questions
What is the Smart (MCC) Forfour MOT pass rate?
78% of the 20,473 Smart (MCC) Forfour first-attempt MOTs in 2025 passed. The fail rate of 22% compares with 22.6% across all cars. A further 5.7% passed after a defect was fixed during the test visit.
What does a Smart (MCC) Forfour usually fail on?
The single most common failure is "Ball joint: ball joint excessively worn", recorded on 688 failed tests, followed by "Tread depth: tread depth below requirements of 1.6mm" and "Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits". By section, suspension appears in 33.9% of failures, tyres appears in 33% of failures, noise, emissions and leaks appears in 24.1% of failures.
Does age change the odds?
Sharply. At 3 to 5 years old the fail rate was 0%; at 14+ years it was 34.6%. The median Smart (MCC) Forfour tested in 2025 was 9 years old with 44,336 miles.
Is the Smart (MCC) Forfour getting less reliable?
The fail rate rose 5.2 points to 22% from 2022 to 2025 while the median one tested aged 3 years. Ageing alone would predict about 7.5 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 Forfour 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 Smart (MCC) models
Checking a particular Forfour?
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.