Mercedes-Benz CLS years to avoid — 69,078 MOT tests ranked

Inspect most carefully: 2017, 2018, 2019. Strongest in the data: 2005. The ranking uses 69,078 MOT tests across 15 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 CLS 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	2005 Strong	111.6	+11.6 pts	76.1%	2,789
2	2006	109.4	+9.4 pts	73.9%	4,152
3	2011	107.9	+7.9 pts	77.1%	3,480
4	2007	107.1	+7.1 pts	72.2%	5,062
5	2008	106.7	+6.7 pts	71.9%	4,020
6	2012	105.6	+5.6 pts	76.8%	3,312
7	2015	103.5	+3.5 pts	82.2%	8,599
8	2010	103.1	+3.1 pts	70.5%	3,175
9	2009	102.9	+2.9 pts	69.3%	3,249
10	2013	102.5	+2.5 pts	75.8%	9,119
11	2014	101.7	+1.7 pts	77.6%	5,329
12	2016	100.9	+0.9 pts	82.2%	6,264
13	2017 Inspect	99.2	-0.8 pts	83.3%	4,439
14	2018 Inspect	97.6	-2.4 pts	83.9%	2,877
15	2019 Inspect	95.7	-4.3 pts	84.1%	3,212

Why 2017 and 2018 and 2019 rank lower

The 2017 cohort passes 83.3% of tests (-0.8 points versus same-age cars) at a median 55,712 miles, with tyres the leading failure system. The 2018 cohort passes 83.9% of tests (-2.4 points versus same-age cars) at a median 46,578 miles, with tyres the leading failure system. The 2019 cohort passes 84.1% of tests (-4.3 points versus same-age cars) at a median 39,081 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.

How to use this before buying

Rankings describe the cohort, not the car. A cherished 2017 example beats a neglected 2005 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 CLS years should I avoid?

Based on 69,078 MOT tests adjusted against cars of the same age, 2017, 2018, 2019 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 CLS year to buy used?

2005 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 CLS reliable overall?

Across 69,078 tests, the median age-adjusted index is 103.1 (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.