Mercedes-Benz B MOT pass rate: 91.6% (7,935 tests, 2025)
Last updated · OBDCode UK editorial
How the B compares
Mercedes-Benz B
91.6%UK average (all Class 4 vehicles)
77.5% across 33.1 million testsMercedes-Benz average (all models)
80.7%What fails most on the Mercedes-Benz B
Across failed and rectified tests in 2025, these vehicle systems produced the most defects on the B:
Scroll horizontally to read every column.
| # | System | Defects recorded | Share |
|---|---|---|---|
| 1 | Tyres | 441 | 47.7% |
| 2 | Brakes | 145 | 15.7% |
| 3 | Suspension | 96 | 10.4% |
| 4 | Seat belts and supplementary restraint systems | 85 | 9.2% |
| 5 | Lamps, reflectors and electrical equipment | 81 | 8.8% |
| 6 | Visibility | 76 | 8.2% |
Pre-MOT checklist for B owners
Based on the failure profile above, ten minutes with a torch before your test removes the most likely fail items:
- Check tread with the 20p test and inspect sidewalls for cracking — tyres close to the limit are the country’s most common advisory
- Feel for a spongy pedal or pulling to one side; check pad wear through the wheel spokes if visible
- Bounce each corner and listen for clonks over speed bumps — suspension is this model’s (and the UK’s) top failure system
- Pull every belt sharply to confirm it locks, and check for cuts and fraying
- Walk round with all lights on: one blown bulb is the most avoidable fail there is
An illuminated engine management light is a Major MOT defect. Read the code, repair the cause, then confirm the light stays off — clearing a code alone is not a repair.
B pass rate by registration year
Scroll horizontally to compare every registration-year column.
| Registration year | Tests | Pass rate | Vs same-age | Median mileage | Pass-rate bar |
|---|---|---|---|---|---|
| 2019 | 10,587 | 91.7% | +3.3 pts | 26,583 | 91.7% visual scale |
| 2020 | 8,219 | 92.8% | +2.9 pts | 22,242 | 92.8% visual scale |
| 2021 | 2,513 | 93.6% | +3.2 pts | 21,581 | 93.6% visual scale |
Same-vehicle follow-up
The defect groups above are a single-year count. The prognosis registry follows the same vehicle_id into the next MOT year. The extracts do not record the repair, a turbo part number, or a gearbox type.
- Tyres: advisory follow-up · did the same fail item hold
- Brakes: advisory follow-up · did the same fail item hold
- Suspension: advisory follow-up · did the same fail item hold
On this model, these certificate lines have a published follow-up (cohort at least 200 cars):
- Brake pads wearing thin — 274 cars · 3.3% failed the same item the next year
- Tread depth worn close to legal limit/worn on edge — 671 cars · 1.5% failed the same item the next year
- Condition slightly damaged/cracking or perishing — 574 cars · 1.2% failed the same item the next year
Check a specific B before you buy
Pass rates describe the model; they can’t tell you about the one car you’re looking at. Run its plate through our free MOT history check to see its personal record of failures, advisories and mileage readings.
Other Mercedes-Benz models
FAQs
What is the MOT pass rate for a Mercedes-Benz B?
In 2025, 91.6% of 7,935 first MOT tests on the Mercedes-Benz B were passes (UK average: 77.5%). Data: DVSA anonymised MOT results.
What does the B fail its MOT on most?
The biggest defect group is tyres (47.7% of its recorded defects), followed by brakes.
Is the Mercedes-Benz B reliable?
MOT pass rate is one lens on durability: at 91.6% it performs above the national average at a median age of 5 years and 30,067 miles. Always check the individual car's history too.
Before you agree to the work
A fault or an advisory is a quote waiting to happen. These pages set out what a garage has to tell you, what a comparable written quote should include, and what you can do if the bill is not what you agreed.
- Estimates, quotes and extra work — what a price has to cover, and when a garage may charge more than it first said.
- What a diagnostic test costs — what the fee should include, and when it should come off the repair.
- Tools — when to buy and when to skip — how to choose a diagnostic tool, and when a garage visit is cheaper than owning one.
- Choosing a garage you can check — what to verify before you hand over the keys.
- Your rights after a car repair — what to do when the work is not right, and how to put it in writing.
Source: DVSA Anonymised MOT tests and results, 2025 extract (Class 4 initial tests only; retests excluded). Contains public sector information licensed under the Open Government Licence v3.0. Figures rounded to one decimal place.