MOT failures by make
Smart MOT failures for “Service brake performance: excessively binding”
Smart cars failed their MOT on “Service brake performance: excessively binding” in 1.32% of 177,310 tests in 2023–2024 (2,342 tests) — 1.7 times as often as comparable cars of the same age, mileage and fuel, which would have failed on it in about 0.77% of tests. It is the number 13 most common failure item on Smarts.
Data to 2024-12-30 · Page updated 2026-09-28 · Publisher: 73 Auto
- Smart tests failing on it
- 1.32%
- 2,342 of 177,310 tests, 2023–2024
- Comparable cars
- 0.77%
- national rate at the same age, mileage and fuel
- Observed ÷ expected
- 1.71×
- 73 Auto analysis · rank #13 for Smart
How unusual this is for the make
Across all MOT failures, Smarts fail 1.06× as often as comparable cars. On this item the gap is 1.61× wider than that overall level, so it is a genuine Smart pattern rather than a reflection of how often the make fails in general. It is a major defect in the brakes part of the test. Nationally it appears on 0.72% of MOT tests.
Smart models and “Service brake performance: excessively binding”
The Smart Fortwo is most affected (2.09× comparable cars); the Smart Forfour least (0.34×). Not every model follows the make: the pattern is concentrated in some models. Model rows compare with cars of the same age and fuel.
| Model | Tests | Failed on it | vs similar cars |
|---|---|---|---|
| Smart Fortwo | 105,250 | 1.92% | 2.09× |
| Smart Forfour | 48,547 | 0.16% | 0.34× |
By age at test
The difference is largest at 11-12 years old: 3.37% of Smart tests against 0.92% for comparable cars.
| Age (years) | Smart tests | Smart | Comparable cars |
|---|---|---|---|
| 3-4 | 12,504 | 0.02% | 0.06% |
| 5-6 | 32,503 | 0.01% | 0.15% |
| 7-8 | 34,330 | 0.06% | 0.39% |
| 9-10 | 15,694 | 1.82% | 0.67% |
| 11-12 | 14,730 | 3.37% | 0.92% |
| 13-15 | 31,521 | 3.48% | 1.41% |
| 16+ | 34,183 | 1.27% | 1.46% |
Other Smart MOT faults that stand out
- Catalyst emissions: Lambda reading after 2nd fast idle outside specified limits · 2.22× comparable cars
- Washers: provides insufficient washer liquid · 1.52× comparable cars
Limitations
Official data: DVSA's anonymised MOT results (2023–2024), class 4 initial tests, cars at least 2.5 years old. 73 Auto analysis: the comparison rate applies the national rate of this item for each test's own age, mileage band and fuel to the Smart tests. An MOT result reflects maintenance, mileage and how a car is used as well as its design, so this is not a measure of which make is most reliable. The wording of the defect is DVSA's.
Has this Smart failed on it before?
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UK number plate or 17-character VIN
Where these figures come from
- Anonymised MOT tests and results (2023 and 2024) — Driver and Vehicle Standards Agency (DVSA). Open Government Licence v3.0.
Figures labelled as 73 Auto estimates are our own analysis of these sources, set out in the methodology and data sources. To report a factual error, see corrections.