Mercedes-Benz C years to avoid: 2020, 2021

Last updated · OBDCode UK editorial

Inspect most carefully: 2020, 2021. Strongest in the data: 2008 or 2010. The ranking uses 1.1 million MOT test records across 21 qualifying registration-year cohorts in the 2023–2025 DVSA test extracts and compares each cohort with all UK cars of the same age. Counts are test records, not unique vehicles. Same-vehicle follow-up for common certificate lines on this model is further down: how often the same item failed the next year, and how often the car was not tested again. Fuel-type signal: diesels show an average 4.4-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 C 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.

RankYearIndexVs same-agePass rateTests
1 2008 Strong 104.4 +4.4 pts 69.6% 42,839
2 2010 Strong 104.4 +4.4 pts 71.8% 42,047
3 2014 104.1 +4.1 pts 79.9% 76,814
4 2001 103.9 +3.9 pts 70.4% 3,928
5 2009 103.8 +3.8 pts 70.2% 40,822
6 2002 103.6 +3.6 pts 69.2% 7,620
7 2015 103.5 +3.5 pts 82.3% 103,035
8 2011 103.4 +3.4 pts 72.5% 60,218
9 2007 102.9 +2.9 pts 68.0% 38,374
10 2016 102.5 +2.5 pts 83.9% 110,346
11 2006 101.3 +1.3 pts 65.7% 30,576
12 2017 101.2 +1.2 pts 85.2% 118,299
13 2013 101.2 +1.2 pts 74.6% 72,438
14 2005 101.2 +1.2 pts 65.7% 26,728
15 2012 101.0 +1.0 pts 72.2% 80,699
16 2018 100.8 +0.8 pts 87.1% 84,470
17 2019 100.4 +0.4 pts 88.8% 71,902
18 2004 100.2 +0.2 pts 64.5% 19,932
19 2003 100.2 +0.2 pts 65.2% 13,765
20 2020 Inspect 99.2 -0.8 pts 89.1% 22,240
21 2021 Inspect 99.0 -1.0 pts 89.4% 3,431

Why 2020 and 2021 rank lower

The 2020 cohort passes 89.1% of tests (-0.8 points versus same-age cars) at a median 30,705 miles, with tyres the leading failure system. The 2021 cohort passes 89.4% of tests (-1.0 points versus same-age cars) at a median 28,435 miles, with tyres 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.

What happened next on this model

Year rankings are age-adjusted pass rates. The figures below are a same-vehicle follow-up for certificate lines that appear often enough on this model (at least 200 cars). They are not a repair quote and they do not isolate a turbo, DSG, or clutch part.

National rankings for the not-retested gap: cars not tested again. Repair-hold rates: repairs that did not hold.

How to use this before buying

  • Rankings describe the cohort, not the car. A cherished 2020 example beats a neglected 2008 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 (4.4 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 C years should I avoid?

Based on 1.1 million MOT tests adjusted against cars of the same age, 2020, 2021 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 C year to buy used?

2008 and 2010 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 C reliable overall?

Across 1.1 million 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.

What data is required before a years-to-avoid guide is published?

We publish a guide only when a model has at least five registration-year cohorts old enough for a routine first MOT, each based on at least 1,500 Class 4 initial MOT tests pooled across the stated DVSA extract years, and at least 60,000 tests across those cohorts. From the models that pass those gates, this release includes the 220 models with the largest pooled samples. Retests are excluded.

How are the Strong and Inspect labels assigned?

Strong considers only the two highest-ranked registration-year cohorts and labels either one that is within 1.5 index points of the best. Inspect considers only the three lowest-ranked cohorts and labels a year only when its index is no higher than 100 and at least 2 points below the model median. Counts are MOT test records, not unique vehicles.

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. Pass rate uses DVSA result codes (P + PRS) ÷ (P + PRS + F): passes and passes after rectification at the test divided by those outcomes plus failures. Class 4 initial-test records only; retests excluded; at least 1,500 records per registration-year cohort. “Strong” considers the top two cohorts within 1.5 index points of the best. “Inspect” considers only the bottom three cohorts, then requires an index no higher than 100 and at least 2 points below the model median. Counts are test records, not unique vehicles. Association is not proof of a model-year defect. Source: DVSA Anonymised MOT tests and results, 2023–2025 extracts. Contains public sector information licensed under the Open Government Licence v3.0.