Mercedes-Benz B-Class MOT pass rate: 74.9% (60,589 tests, 2025)
Last updated · OBDCode UK editorial
How the B-Class compares
Mercedes-Benz B-Class
74.9%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-Class
Across failed and rectified tests in 2025, these vehicle systems produced the most defects on the B-Class:
Scroll horizontally to read every column.
| # | System | Defects recorded | Share |
|---|---|---|---|
| 1 | Suspension | 9,367 | 26.3% |
| 2 | Lamps, reflectors and electrical equipment | 6,999 | 19.6% |
| 3 | Brakes | 6,268 | 17.6% |
| 4 | Tyres | 5,431 | 15.2% |
| 5 | Body, chassis, structure | 2,508 | 7.0% |
| 6 | Visibility | 2,360 | 6.6% |
Pre-MOT checklist for B-Class owners
Based on the failure profile above, ten minutes with a torch before your test removes the most likely fail items:
- Bounce each corner and listen for clonks over speed bumps — suspension is this model’s (and the UK’s) top failure system
- Walk round with all lights on: one blown bulb is the most avoidable fail there is
- Feel for a spongy pedal or pulling to one side; check pad wear through the wheel spokes if visible
- Check tread with the 20p test and inspect sidewalls for cracking — tyres close to the limit are the country’s most common advisory
- Look underneath for corrosion around sills and subframes, especially on older cars
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-Class pass rate by registration year
Lower age-adjusted outliers to inspect carefully: 2007, 2008, 2011. Strongest age-adjusted years: 2012, 2013. Full ranking and method: Mercedes-Benz B-Class years to avoid.
Scroll horizontally to compare every registration-year column.
| Registration year | Tests | Pass rate | Vs same-age | Median mileage | Pass-rate bar |
|---|---|---|---|---|---|
| 2006 | 6,041 | 63.8% | -0.6 pts | 98,886 | 63.8% visual scale |
| 2007 | 7,995 | 63.9% | -1.2 pts | 99,321 | 63.9% visual scale |
| 2008 | 10,406 | 62.7% | -2.5 pts | 97,458 | 62.7% visual scale |
| 2009 | 12,889 | 65.2% | -1.2 pts | 92,433 | 65.2% visual scale |
| 2010 | 13,526 | 66.2% | -1.2 pts | 85,871 | 66.2% visual scale |
| 2011 | 10,564 | 66.5% | -2.6 pts | 80,290 | 66.5% visual scale |
| 2012 | 17,149 | 74.8% | +3.6 pts | 80,882 | 74.8% visual scale |
| 2013 | 21,050 | 76.9% | +3.6 pts | 74,321 | 76.9% visual scale |
| 2014 | 24,472 | 78.1% | +2.3 pts | 68,341 | 78.1% visual scale |
| 2015 | 16,801 | 82.2% | +3.5 pts | 59,568 | 82.2% visual scale |
| 2016 | 15,871 | 84.3% | +2.9 pts | 50,762 | 84.3% visual scale |
| 2017 | 16,858 | 85.2% | +1.2 pts | 44,116 | 85.2% visual scale |
| 2018 | 11,468 | 87.7% | +1.4 pts | 34,166 | 87.7% visual scale |
| 2019 | 1,754 | 91.2% | +2.8 pts | 26,476 | 91.2% 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.
- Suspension: advisory follow-up · did the same fail item hold
- Brakes: advisory follow-up · did the same fail item hold
- Tyres: advisory follow-up · did the same fail item hold
- Body, chassis, structure: 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):
- Shock absorbers has light misting of oil — 799 cars · 9.5% failed the same item the next year
- Ball joint has slight play — 1,062 cars · 9.5% failed the same item the next year
- Individual direction indicators slightly discoloured — 455 cars · 7.7% failed the same item the next year
- Exhaust system has a minor leak of exhaust gases — 273 cars · 6.2% failed the same item the next year
- Rigid brake pipes corroded, covered in grease or other material — 3,070 cars · 5.7% failed the same item the next year
Check a specific B-Class 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-Class?
In 2025, 74.9% of 60,589 first MOT tests on the Mercedes-Benz B-Class were passes (UK average: 77.5%). Data: DVSA anonymised MOT results.
What does the B-Class fail its MOT on most?
The biggest defect group is suspension (26.3% of its recorded defects), followed by lamps, reflectors and electrical equipment.
Is the Mercedes-Benz B-Class reliable?
MOT pass rate is one lens on durability: at 74.9% it performs below the national average at a median age of 12 years and 74,688 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.