Mercedes-Benz B-Class common problems and MOT pass rate

In 2025, DVSA recorded 71,083 initial MOT tests on the Mercedes-Benz B-Class in Great Britain, and 72.6% passed first time. Here is where the rest failed.

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Mercedes-Benz B-Class at the MOT, 2025

Initial MOT tests: 71,083
Passed first timeAll cars and vans: 72.1%: 72.6%
Failed at firstIncluding 4.7% repaired at the test and passed (PRS): 27.4%
Had a dangerous defectAll cars and vans: 7.3%: 7.2%
Licensed in the UKEnd of 2026 Q2, plus 3,265 off the road (SORN): 67,395

Contains DVSA MOT data, Open Government Licence v3.0, year 2025.

Failure areas

Where the B-Class fails its MOT

The share of initial tests in 2025 with at least one fail or PRS item in each part of the MOT. A test can fail in more than one area, so these do not add up to the fail rate.

1Lamps, reflectors and electrical equipment
9.8%
Headlamps and their aim, brake lights, indicators, fog and reversing lamps, warning lights, battery and wiringAll cars and vans: 10.8%
2Suspension
9.5%
Springs, shock absorbers, suspension arms and bushes, anti-roll bars, wheel bearings and axlesAll cars and vans: 9.0%
3Tyres
6.8%
Tread depth, cuts and bulges, the right size and type, valves and tyre pressure warning systemsAll cars and vans: 6.2%
4Brakes
5.7%
Pedal and handbrake, pipes and hoses, discs, pads and drums, and how well the car stopsAll cars and vans: 6.4%
5Visibility
3.9%
The driver's view, windscreen damage, wipers, washers and mirrorsAll cars and vans: 4.4%
6Noise, emissions and leaks
3.2%
Exhaust emissions and smoke, exhaust noise and fluid leaksAll cars and vans: 3.2%
7Body, chassis and structure
2.9%
Corrosion and damage to the structure, the exhaust system, fuel system, doors, seats, towbar, bumpers and engine mountingsAll cars and vans: 3.3%
8Seat belts and airbags
1.4%
Seat belts, airbags and the airbag warning lightAll cars and vans: 1.0%
9Road wheels
0.8%
Damaged or loose wheels, wheel nuts and hubsAll cars and vans: 0.4%
10Steering
0.4%
Steering rack, joints and linkages, power steering, the steering wheel and columnAll cars and vans: 2.0%

This modelAll cars and vans

Parts

The parts that fail most

Share of initial tests with a fail or PRS item on each part, 2025.

ConditionTyres5.1%
Anti-roll barsSuspension4.0%
SpringsSuspension3.7%
Exhaust emissionsEmissions and leaks3.1%
Headlamp aimLamps and electrics2.9%
WashersVisibility2.4%
Brake performanceBrakes2.4%
Mechanical brake componentsBrakes2.4%

By age

Pass rate by year first used

Older cars fail more often, so compare a car with others of its year. Cars up to 25 years old; years with fewer than 250 tests are left out.

First used	Tests	Passed first time	Dangerous defect
2022	1,315	91.0%	2.0%
2021	1,814	91.7%	2.4%
2020	2,923	90.0%	3.5%
2019	4,305	89.2%	3.6%
2018	3,973	83.5%	6.4%
2017	5,693	80.4%	5.9%
2016	5,360	79.2%	5.9%
2015	5,678	76.6%	6.6%
2014	8,209	71.8%	7.4%
2013	7,004	71.1%	7.9%
2012	5,758	69.3%	8.6%
2011	3,392	58.8%	9.3%
2010	4,337	58.2%	9.6%
2009	4,021	58.2%	10.0%
2008	3,081	55.2%	11.2%
2007	2,234	55.6%	9.4%
2006	1,613	56.4%	9.9%
2005	328	54.3%	7.6%

Mileage

B-Class mileage by age

The median reading at the test: half the cars of that age had covered more, half less. Estimated from 1,000-mile bands, for cars up to 25 years old.

A car well above or below the typical figure is not a problem in itself, but the readings should rise steadily from one MOT to the next. A fall, or a long gap, is worth asking about.

Check a car's mileage record

Age at test	Median mileage	Readings
2 years	19,300 miles	999
3 years	24,100 miles	1,655
4 years	27,900 miles	2,430
5 years	31,600 miles	4,064
6 years	37,900 miles	3,901
7 years	47,500 miles	4,390
8 years	54,400 miles	5,687
9 years	62,000 miles	5,233
10 years	70,500 miles	6,720
11 years	77,800 miles	8,216
12 years	83,200 miles	6,227
13 years	85,700 miles	3,883
14 years	86,800 miles	4,259
15 years	92,700 miles	4,402
16 years	100,200 miles	3,411
17 years	99,000 miles	2,506
18 years	100,100 miles	1,952
19 years	99,600 miles	993

Checking a particular B-Class?

Averages tell you what to look at. The registration tells you about this car: every MOT since 2005 with its failures and advisories, each mileage reading, and whether it is taxed.

Questions

Mercedes-Benz B-Class: common questions

Contains DVSA MOT data, Open Government Licence v3.0, year 2025.

What is the most common MOT failure on the Mercedes-Benz B-Class?

In DVSA's 2025 test records, the area that failed most often on the Mercedes-Benz B-Class was lamps, reflectors and electrical equipment: 9.8% of initial tests had at least one fail or PRS item there, against 10.8% for all cars and vans. Next came suspension (9.5%) and tyres (6.8%).

What is the MOT pass rate for the Mercedes-Benz B-Class?

72.6% of 71,083 initial MOT tests on the Mercedes-Benz B-Class in 2025 were a pass first time. Another 4.7% passed after small repairs made at the test station within the hour (PRS). Across all cars and vans, 72.1% passed first time.

Does a lower pass rate mean the Mercedes-Benz B-Class is unreliable?

Not on its own. MOT results depend on age, mileage and upkeep as much as on design, so a model with many older cars on the road will usually fail more often. The table by year compares cars of a similar age. What matters most is the record of the car you are looking at, so check its MOT history before you buy.

What counts as a dangerous defect?

One the tester judges to be a direct and immediate risk to road safety, or to have a serious impact on the environment. The car fails and should not be driven until it is repaired. 7.2% of initial tests on the Mercedes-Benz B-Class found at least one, against 7.3% for all cars and vans.

Where do these figures come from?

From DVSA's anonymised MOT test data for 2025, published under the Open Government Licence. We count initial tests on cars and light vans in Great Britain, as DVSA does in its own statistics: retests, appeals and abandoned tests are left out, and so are advisories and minor defects.

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