Mercedes-Benz B-Class years to avoid — 186,844 MOT tests ranked

Inspect most carefully: 2007, 2008, 2011. Strongest in the data: 2012 or 2013. The ranking uses 186,844 MOT tests across 14 registration years (2023–2025) and compares each year with all UK cars of the same age. Fuel-type signal: diesels show an average 5.0-point pass-rate deficit on this model. That may reflect mileage and use as well as the car itself, so inspect DPF and emissions history rather than treating fuel type as a verdict.

Every B-Class year, ranked

The age-adjusted MOT index sets 100 as the pass rate of all UK cars registered in the same year and tested in the same calendar year. Higher is better. This prevents an old car being labelled a “bad year” simply because it is old.

Rank	Year	Index	Vs same-age	Pass rate	Tests
1	2013 Strong	103.6	+3.6 pts	76.9%	21,050
2	2012 Strong	103.6	+3.6 pts	74.8%	17,149
3	2015	103.5	+3.5 pts	82.2%	16,801
4	2016	102.9	+2.9 pts	84.3%	15,871
5	2019	102.8	+2.8 pts	91.2%	1,754
6	2014	102.3	+2.3 pts	78.1%	24,472
7	2018	101.4	+1.4 pts	87.7%	11,468
8	2017	101.2	+1.2 pts	85.2%	16,858
9	2006	99.4	-0.6 pts	63.8%	6,041
10	2010	98.8	-1.2 pts	66.2%	13,526
11	2009	98.8	-1.2 pts	65.2%	12,889
12	2007 Inspect	98.8	-1.2 pts	63.9%	7,995
13	2008 Inspect	97.5	-2.5 pts	62.7%	10,406
14	2011 Inspect	97.4	-2.6 pts	66.5%	10,564

Why 2007 and 2008 and 2011 rank lower

The 2007 cohort passes 63.9% of tests (-1.2 points versus same-age cars) at a median 99,321 miles, with brakes the leading failure system. The 2008 cohort passes 62.7% of tests (-2.5 points versus same-age cars) at a median 97,458 miles, with suspension the leading failure system. The 2011 cohort passes 66.5% of tests (-2.6 points versus same-age cars) at a median 80,290 miles, with lamps, reflectors and electrical equipment the leading failure system. This is population-level evidence, not a known-fault list: service history, engine version and the individual MOT record can outweigh the registration-year average.

How to use this before buying

Rankings describe the cohort, not the car. A cherished 2007 example beats a neglected 2012 one — always run the specific reg through the free MOT history check.
Read the advisories. Repeated notes for the same component across years mean the owner has been ignoring it. Decode them in our advisory library.
Fuel matters on this model. The diesel deficit (5.0 points) usually traces to DPF and emissions kit on low-mileage use — check for P2463-type soot codes on the test drive.
Scan before you pay. A 2-minute OBD scan reveals stored faults the dashboard hides — see our scanner guide.

FAQs

Which B-Class years should I avoid?

Based on 186,844 MOT tests adjusted against cars of the same age, 2007, 2008, 2011 are the lower-scoring outliers. That is a prompt for closer inspection, not proof that every car from those years is bad.

What is the best B-Class year to buy used?

2012 and 2013 lead the age-adjusted MOT ranking. The score compares each registration year with all UK cars of the same age; the specific car's history and condition still take priority.

Is the B-Class reliable overall?

Across 186,844 tests, the median age-adjusted index is 101.3 (100 equals the pass rate of all cars registered in the same year). Use the spread between years as one signal, then check the individual registration.

Methodology: index = 100 + the model-year cohort’s MOT pass-rate difference versus all UK vehicles registered in the same year and tested in the same calendar year. Class 4 initial tests only; retests excluded; at least 1,500 tests per page. “Inspect” years are below both the same-age baseline and the model’s median index by at least 2 points. Association is not proof of a model-year defect. DVSA anonymised data 2023–2025, OGL v3.0.