Mercedes-Benz B MOT reliability

Mercedes-Benz Bs passed their MOT first time 90% of the time across 9,973 tests in 2025.

First-time pass rate

90%

MOTs analysed

9,973

Still licensed (GB)

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Body type

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Pass rate by year of first registration

Older cars fail more often, so compare a car with others of the same age. Years with very few MOTs can show extreme pass rates, even 0% or 100%, so give more weight to years with more tests.

In detail:

First registered

2021 petrol

938 MOTs

Passed first time 92%. Typical mileage 22,482 (most between 15,236 and 32,346).

2021: 100% → 2022: 100% → 2023: 91% → 2024: 91% → 2025: 92%

Most common failures

Condition: has a cut in excess of the requirements deep enough to reach the ply or cords (2.7%)
Headlamp aim: too low (1.0%)
Wipers: does not clear the windscreen effectively (1.0%)
Condition: has ply or cords exposed (0.9%)
Tread depth below requirements of 1.6mm (0.5%)

2021 diesel

542 MOTs

Passed first time 93%. Typical mileage 27,832 (most between 20,572 and 37,886).

2022: 100% → 2023: 100% → 2024: 91% → 2025: 93%

Most common failures

Condition: has a cut in excess of the requirements deep enough to reach the ply or cords (1.7%)
Wipers: does not clear the windscreen effectively (1.1%)
Headlamp aim: too high (0.7%)
Condition: has ply or cords exposed (0.7%)
SRS malfunction indicator lamp: warning lamp indicates a fault (0.6%)

2021 hybrid

330 MOTs

Passed first time 90%. Typical mileage 27,813 (most between 18,635 and 43,004).

2023: 100% → 2024: 89% → 2025: 90%

Most common failures

Condition: has a cut in excess of the requirements deep enough to reach the ply or cords (3.6%)
Condition: has ply or cords exposed (1.2%)
Wipers: does not clear the windscreen effectively (0.9%)
Condition: has a bulge, caused by separation or partial failure of its structure (0.9%)
Headlamp: insecure (0.6%)

Where 2021 Bs fail

Wheels & tyres

4.8%

Lights & electrics

1.5%

Visibility & wipers

1.2%

Brakes

0.6%

Suspension & axles

0.5%

Exhaust, emissions & leaks

0.3%

Seat belts & other equipment

0.2%

Body, structure & corrosion

0.1%

Looking at a particular car?

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Based on 2025 initial MOT tests in DVSA's anonymised MOT dataset (cars and light vans). Contains public sector information licensed under the Open Government Licence v3.0. Model details: Vehicle data by VehiclesDB.