At a glance
How 4,152 first tests went in 2025.
- Passed first time
- 58 in every 100
- Did not pass first time
- 42 in every 1001,739 failed first-attempt tests
- The typical car
- 15 yearsabout 88,839 miles
- First tests counted
- 4,152
What failed most often
- Drive shaft joints and boots (front)11 in every 100 failed tests
- Suspension arm ball joint (front)11 in every 100 failed tests
- Side repeater indicators10 in every 100 failed tests
How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.
These are patterns across 2010 Mercedes-Benz B-Class vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.
Brakes
Two faults. The strongest is the brake efficiency below minimum (roller test): 6.9 times as often as on similar cars.
Figures below are measured across the 1,738 of 1,739 failed first attempts (99.9%) that recorded an odometer reading in 2025. Mileage is needed to compare like with like.
We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.
Brake efficiency below minimum (roller test)
Rigid brake pipes (rear)
What it means
Chafing, corrosion or damage to a rigid brake pipe justifies rejection once its wall thickness is reduced by a set amount, although DVSA accepts this is not easy to determine. If a tester is not sure, the benefit of the doubt applies. A leaking pipe or connection is graded Dangerous on a hydraulic system and Major on an air system.
Also noted as an advisory
Testers also noted it as an advisory, worn but not yet failing, on 285 first tests, 3.8 times as often as on similar cars.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage. Advisories count notes recorded on failed first tests only.
Lamps and electrical
Two faults. The strongest is the side repeater indicators (front): 6.6 times as often as on similar cars.
Side repeater indicators (front)
What it means
Sequential or dynamic direction indicators are not a reason to fail. Where a side repeater is required, it is allowed to be part of the front direction indicator if it has a marked wraparound lens, or an amber light coming through the front lens when viewed from a set distance to the side of the rear bumper. A lens defect with no effect on the emitted light is Minor, and one that adversely affects the light is Major.
Individual direction indicators (rear)
What it means
Direction indicators must be amber, though vehicles first used before a set date may have white at the front and red at the rear when the indicators are combined with stop or position lamps, and sequential or dynamic ones are not a reason to fail. A lamp that is missing, inoperative or has more than half of a multiple light source not functioning is graded Major. A flashing rate outside the permitted range is graded Minor.
Also noted as an advisory
Testers also noted it as an advisory, worn but not yet failing, on 81 first tests, 2.5 times as often as on similar cars.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage. Advisories count notes recorded on failed first tests only.
Suspension
Three faults. The strongest is the shock absorbers (front): 3.0 times as often as on similar cars.
Shock absorbers (front)
What it means
Slight seepage that leaves a film of fluid on a shock absorber does not fail it. Severe leakage, or damage so that it does not function, is Major. A shock absorber missing or likely to become detached is graded Dangerous, though a missing one is only rejected if shock absorbers were fitted as standard.
Coil spring (rear)
What it means
A missing bump stop rubber is not a reason to fail a coil spring. When the vehicle is jacked and lowered, a spring that does not correctly locate as the suspension returns to its normal running position is rejected as insecurely attached. A missing spring is Major, and graded Dangerous where directional control is affected.
Anti-roll bar ball joint dust cover (front)
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Noise, emissions and leaks
Two faults. The strongest is the petrol engine warning light: 2.5 times as often as on similar cars.
Petrol engine warning light
What it means
The malfunction indicator lamp (MIL) on a petrol engine is a Major failure when it is illuminated indicating a malfunction. The detail line DVSA gives for the same row also names an inoperative lamp. The test covers only certain petrol vehicles, depending on their age, size and fuel type.
Diesel engine warning light
What it means
An engine malfunction indicator lamp that is illuminated to show a malfunction is graded Major on a diesel, but only on the diesels the test covers, which depends on the vehicle type and when it was first used. DVSA lists it under exhaust emissions for compression ignition engines, and the detail line for the row also names an inoperative lamp.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Body and structure
One fault: drive shaft joints and boots (front), 2.3 times as often as on similar cars.
Drive shaft joints and boots (front)
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Advisories
Other things testers noted as worn or close to failing, more often than on similar cars.
An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail. Advisories for the faults above are shown with those faults.
Rigid brake pipes (front)
Seat belt condition (rear)
Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.
MOT pass rates
How first tests ended, and how the pass rates are counted.
- Passed first time
- 58in every 100
- Passed on the first test.
- Fixed at the station
- 8in every 100
- Failed, then fixed at the test station the same day.
- Failed
- 34in every 100
- Did not pass, and were not fixed at the test station.
First-attempt pass 58.1% of 4,152 first tests (2025): only cars that passed first time count. Official-style pass 65.6%: cars fixed at the test station also count as a pass. The 8 fixed and the 34 not fixed make the 42 in every 100 that did not pass first time.
Petrol and diesel
Figures are in every 100 first tests. Cars with more miles usually fail more often, so the same-mileage figure gives every fuel the mileage mix of all the cars in this year.
Same model, other years
Passed first time in every 100, all tested in 2025.
Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 57 in every 100 passed first time.
| Year | Passed first time | First tests |
|---|---|---|
| 2005 | 53 in every 100 | 309 |
| 2006 | 56 in every 100 | 1,552 |
| 2007 | 55 in every 100 | 2,116 |
| 2008 | 55 in every 100 | 2,936 |
| 2009 | 58 in every 100 | 3,849 |
| 2010 This car | 58 in every 100 | 4,152 |
| 2011 | 58 in every 100 | 3,257 |
| 2012 | 69 in every 100 | 5,571 |
| 2013 | 71 in every 100 | 6,793 |
| 2014 | 71 in every 100 | 7,934 |
| 2015 | 76 in every 100 | 5,481 |
| 2016 | 79 in every 100 | 5,183 |
| 2017 | 80 in every 100 | 5,502 |
| 2018 | 83 in every 100 | 3,858 |
| 2019 | 89 in every 100 | 4,149 |
| 2020 | 90 in every 100 | 2,786 |
| 2021 | 92 in every 100 | 1,727 |
| 2022 | 91 in every 100 | 1,216 |
If you are buying one
What this year's MOT record means for the decision in front of you.
Mileage matters most on a 2010 B-Class.
Of 2010 B-Class vehicles with under 65,000 miles, 69 in every 100 passed their 2025 MOT first time. With 117,000 miles or more, 48 in every 100 did.
Petrol or diesel?
| Typical mileage | Passed first time, as tested | Passed first time, same mileage | |
|---|---|---|---|
| Petrol | 83,416 miles | 60 | 58 |
| Diesel | 97,310 miles | 56 | 58 |
Figures are in every 100 first tests. Petrol cars look better on the raw figures only because diesel cars have done more miles (typically 97,310 against 83,416). At the same mileage there is no clear difference between the two.
What to check at your mileage
How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.
| Under 65,000 | 82,000–97,000 | 117,000 and over | |
|---|---|---|---|
| Drive shaft joints and boots (front) | 1.5 | 5.0 | 7.3 |
| Suspension arm ball joint (front) | 1.1 | 5.5 | 7.1 |
| Side repeater indicators | 3.5 | 4.8 | 3.4 |
| Coil spring (rear) | 2.1 | 3.5 | 5.8 |
| Handbrake efficiency below minimum (roller test) | 1.1 | 3.9 | 6.9 |
Faults per 100 first tests, by the car's mileage at the test.
When a car fails
of failed cars had one item to fix.
of failed cars had three or more items to fix.
of all first tests had a defect the tester marked dangerous (unsafe to drive away).
Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.
FAQs
Short answers about how to read this model-year guide.
About this data
How this page is built and what it can (and can't) say.
These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.
What we include
UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.
Same-day repairs
PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.
How we compare
We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.
What this does not cover
- MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
- Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
- Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
- If the data for a car is too thin to say anything useful, we say so rather than guess.
Contains public sector information licensed under the Open Government Licence v3.0.
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