Mercedes-Benz B-Class MOT pass rate and common failures
In 2025, 72.4% of Mercedes-Benz B-Class MOT tests were a first-time pass, across 70,069 tests in Great Britain. For all cars it was 71.5%.
Compared with cars of the same age
Older cars fail more often, so a model that’s mostly a few years old will look better than one that’s mostly 12. These figures compare like with like.
At 3–5 years
90.3%
All cars: 86.1% (4.2 points better). 8,148 tests.
At 6–10 years
78.8%
All cars: 76.1% (2.7 points better). 25,943 tests.
At 11 years and over
63.6%
All cars: 61.3% (2.3 points better). 35,978 tests.
Pass rate by age
Figures by age, with typical mileage
| Age (years) | Tests | First-time pass | All cars | Typical mileage |
|---|---|---|---|---|
| 3 | 1,655 | 90.9% | 87.8% | 23,750 miles |
| 4 | 2,462 | 90.7% | 86.4% | 28,750 miles |
| 5 | 4,031 | 89.8% | 84.5% | 31,250 miles |
| 6 | 3,901 | 85.6% | 81.9% | 38,750 miles |
| 7 | 4,393 | 81.4% | 79.3% | 46,250 miles |
| 8 | 5,729 | 80.3% | 76.3% | 53,750 miles |
| 9 | 5,198 | 77.0% | 73.1% | 61,250 miles |
| 10 | 6,722 | 73.2% | 70.0% | 71,250 miles |
| 11 | 8,219 | 71.9% | 66.9% | 78,750 miles |
| 12 | 6,262 | 69.8% | 64.4% | 83,750 miles |
| 13 | 3,849 | 65.1% | 62.1% | 86,250 miles |
| 14 | 4,258 | 58.6% | 60.2% | 86,250 miles |
| 15 | 4,404 | 58.3% | 58.6% | 93,750 miles |
| 16 | 3,435 | 57.0% | 57.5% | 101,250 miles |
| 17 | 2,503 | 56.3% | 57.2% | 98,750 miles |
| 18 | 1,967 | 54.8% | 57.0% | 101,250 miles |
| 19 | 1,009 | 56.1% | 57.2% | 98,750 miles |
| 20+ | 72 | 52.8% | 61.4% | 106,250 miles |
Typical mileage is the median reading at the test, to the nearest 2,500 miles.
What fails most often
The share of Mercedes-Benz B-Class MOT tests that failed on at least one item in each area, against all cars. A test can fail on several areas at once.
| Area | B-Class | All cars |
|---|---|---|
| Lamps, reflectors and electrical equipment | 13.7% | 16.6% |
| Suspension | 13.4% | 13.7% |
| Brakes | 9.0% | 10.2% |
| Tyres | 8.8% | 8.4% |
| Visibility | 4.5% | 5.2% |
| Body, chassis, structure | 3.7% | 4.2% |
| Noise, emissions and leaks | 3.4% | 4.0% |
| Seat belts and supplementary restraint systems | 1.5% | 1.1% |
Most common reasons for failing
- Coil spring: fractured or broken failed 4.2% of tests · what this means
- Linkage ball joint dust cover: ball joint dust cover no longer prevents the ingress of dirt failed 3.4% of tests · what this means
- Malfunction indicator lamp: inoperative or indicates a malfunction failed 2.5% of tests · what this means
- Joints: constant velocity boot split or insecure, no longer prevents the ingress of dirt failed 2.5% of tests
- Ball joint excessively worn failed 2.3% of tests · what this means
- Registration plate lamp(s): inoperative in the case of a single lamp or all lamps failed 2.3% of tests · what this means
- Condition: has a cut in excess of the requirements deep enough to reach the ply or cords failed 2.1% of tests
- Tread depth below requirements of 1.6mm failed 1.9% of tests
- Brake pads: less than 1.5 mm thick failed 1.9% of tests · what this means
- Condition: has ply or cords exposed failed 1.8% of tests
Checking a particular B-Class?
See its own MOT history, mileage record and advisories in plain English. Free, no sign-up.
About these figures
- They cover every B-Class version DVSA records under this name (engines, trims and generations together), on its first MOT test of each visit. A “pass with rectification” (fixed within an hour) counts as a fail, as in DVSA’s own statistics.
- Cars under three years old are left out, because the few tested that young are mostly taxis.
- Fuel mix of the cars tested: diesel 63.7%, petrol 35.1%, hybrid electric (clean) 0.6%.
- A pass rate describes the model, not any one car. How a car has been looked after matters more.
Download these figures (CSV) · Other Mercedes-Benz models · All makes
Source: DVSA anonymised MOT test data for 2025. Contains public sector information licensed under the Open Government Licence v3.0. Our own analysis; not produced or endorsed by DVSA.