Mercedes-Benz B-Class MOT reliability

Mercedes-Benz B-Classs passed their MOT first time 56% of the time across 32 tests in 2025. 66,046 are still licensed in Great Britain.

Example photo of a Mercedes-Benz B-Class — Photo: Dinkun Chen · CC BY-SA 4.0 · Wikimedia Commons

These figures come from 32 MOT tests. That's a fairly small number of cars, so they may not be typical of these cars as a whole.

First-time pass rate

56%

MOTs analysed

32

Still licensed (GB)

66,046

Body type

–

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

2009 petrol

6 MOTs

These figures come from only 6 MOT tests. With so few cars, a single pass or fail changes the percentages a lot, so treat them as a rough guide rather than a true average.

Passed first time 67%. Typical mileage 82,018 (most between 63,701 and 97,926).

2012: 88% → 2013: 63% → 2014: 75% → 2015: 100% → 2016: 86% → 2017: 78% → 2018: 71% → 2019: 75% → 2020: 50% → 2021: 57% → 2022: 86% → 2023: 83% → 2024: 67% → 2025: 67%

Most common failures

Ball joint excessively worn (33.3%)
Linkage ball joint dust cover: ball joint dust cover no longer prevents the ingress of dirt (33.3%)
Headlamp aim: projected beam image is obviously incorrect (16.7%)

2009 diesel

2 MOTs

These figures come from only 2 MOT tests. With so few cars, a single pass or fail changes the percentages a lot, so treat them as a rough guide rather than a true average.

Passed first time 50%. Typical mileage 134,250 (most between 110,689 and 157,810).

2012: 67% → 2013: 67% → 2014: 33% → 2015: 100% → 2016: 67% → 2017: 67% → 2018: 67% → 2019: 100% → 2020: 25% → 2021: 67% → 2022: 67% → 2023: 100% → 2024: 50% → 2025: 50%

Most common failures

Headlamp aim: too low and too far to the left. (50.0%)

Where 2009 B-Classs fail

Suspension & axles

33.3%

Lights & electrics

16.7%

Looking at a particular car?

See its own MOT history, mileage and red flags, compared with these figures. Free.

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.