2018 Mercedes-Benz B-Class MOT pass rate: 87.7% (11,468 tests)
Is the 2018 B-Class getting worse?
Pass rate of 2018-registered cars across recent test years:
| Test year | Pass rate | |
|---|---|---|
| 2023 | 89.4% +1.3 vs same-age |
|
| 2024 | 87.7% +1.5 vs same-age |
|
| 2025 | 86.0% +1.3 vs same-age |
The raw rate normally falls as cars age. The “vs same-age” figure compares this cohort with all UK cars registered in the same year, so normal ageing is not mistaken for a bad model year.
What fails on a 2018 B-Class
| # | System | Defects recorded | Share |
|---|---|---|---|
| 1 | Tyres | 937 | 45.6% |
| 2 | Lamps, reflectors and electrical equipment | 365 | 17.8% |
| 3 | Brakes | 210 | 10.2% |
| 4 | Suspension | 172 | 8.4% |
| 5 | Visibility | 163 | 7.9% |
| 6 | Noise, emissions and leaks | 69 | 3.4% |
All B-Class years compared
| Registration year | Tests | Pass rate | Vs same-age | Median mileage |
|---|---|---|---|---|
| 2006 | 6,041 | 63.8% | -0.6 pts | 98,886 |
| 2007 | 7,995 | 63.9% | -1.2 pts | 99,321 |
| 2008 | 10,406 | 62.7% | -2.5 pts | 97,458 |
| 2009 | 12,889 | 65.2% | -1.2 pts | 92,433 |
| 2010 | 13,526 | 66.2% | -1.2 pts | 85,871 |
| 2011 | 10,564 | 66.5% | -2.6 pts | 80,290 |
| 2012 | 17,149 | 74.8% | +3.6 pts | 80,882 |
| 2013 | 21,050 | 76.9% | +3.6 pts | 74,321 |
| 2014 | 24,472 | 78.1% | +2.3 pts | 68,341 |
| 2015 | 16,801 | 82.2% | +3.5 pts | 59,568 |
| 2016 | 15,871 | 84.3% | +2.9 pts | 50,762 |
| 2017 | 16,858 | 85.2% | +1.2 pts | 44,116 |
| 2018 (this page) | 11,468 | 87.7% | +1.4 pts | 34,166 |
| 2019 | 1,754 | 91.2% | +2.8 pts | 26,476 |
Weighing up which year to buy? See the full ranking: Mercedes-Benz B-Class years to avoid.
- Free MOT history checkThe exact car’s failures, advisories and mileage trail — sellers can’t edit it
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- XTOOL diagnostic toolsXTOOL code readers for petrol and diesel cars
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FAQs
Is a 2018 Mercedes-Benz B-Class reliable?
2018-registered examples passed 87.7% of their MOT tests (11,468 tests, 2023–2025), +1.4 points versus all UK cars registered in the same year. At roughly 8 years old with a median 34,166 miles, condition now varies car by car — always check the individual MOT history.
What mileage is too high for a 2018 B-Class?
The median tested example shows 34,166 miles. Anything far beyond that isn't automatically bad — a motorway-mile car with consistent service records often beats a low-mileage school-run car — but price accordingly and scrutinise the mileage trail for gaps or drops.
Should I buy the petrol or diesel 2018 B-Class?
In this cohort petrols pass 89.4% of tests against 86.0% for diesels. Mileage and use can explain part of that gap, so treat it as a reason to inspect DPF and emissions history, not a fuel-type verdict.
Source: DVSA Anonymised MOT tests and results, 2023–2025 extracts (96 million Class 4 initial tests; retests excluded). Only vehicles old enough for a routine first MOT are included. Age-adjusted figures compare the model-year cohort with all vehicles of the same registration year tested in the same calendar year. Contains public sector information licensed under OGL v3.0.