2021 Mercedes-Benz C MOT pass rate: 89.4% (3,431 tests)

2021-registered Mercedes-Benz Cs passed 89.4% of 3,431 MOT tests in 2023–2025 — 1.0 points worse than same-age cars (90.4%). This is one of the lower-scoring C years after correcting for vehicle age — inspect the individual car carefully.

89.4%Pass rate, 2021 cars

99.0Age-adjusted index (100 = average)

3,431Tests analysed

28,435 miMedian mileage at test

88.9% / 89.0%Petrol vs diesel pass rate

Is the 2021 C getting worse?

Pass rate of 2021-registered cars across recent test years:

Test year	Pass rate
2024	90.1% -0.6 vs same-age
2025	88.8% -1.4 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 2021 C

#	System	Defects recorded	Share
1	Tyres	388	65.1%
2	Visibility	43	7.2%
3	Brakes	40	6.7%
4	Road Wheels	37	6.2%
5	Lamps, reflectors and electrical equipment	23	3.9%
6	Suspension	22	3.7%

All C years compared

Registration year	Tests	Pass rate	Vs same-age	Median mileage
2001	3,928	70.4%	+3.9 pts	95,942
2002	7,620	69.2%	+3.6 pts	97,981
2003	13,765	65.2%	+0.2 pts	106,702
2004	19,932	64.5%	+0.2 pts	111,997
2005	26,728	65.7%	+1.2 pts	116,417
2006	30,576	65.7%	+1.3 pts	112,864
2007	38,374	68.0%	+2.9 pts	114,690
2008	42,839	69.6%	+4.4 pts	116,300
2009	40,822	70.2%	+3.8 pts	114,357
2010	42,047	71.8%	+4.4 pts	106,426
2011	60,218	72.5%	+3.4 pts	105,237
2012	80,699	72.2%	+1.0 pts	98,799
2013	72,438	74.6%	+1.2 pts	92,208
2014	76,814	79.9%	+4.1 pts	85,486
2015	103,035	82.3%	+3.5 pts	80,236
2016	110,346	83.9%	+2.5 pts	69,279
2017	118,299	85.2%	+1.2 pts	56,785
2018	84,470	87.1%	+0.8 pts	47,061
2019	71,902	88.8%	+0.4 pts	37,683
2020	22,240	89.1%	-0.8 pts	30,705
2021 (this page)	3,431	89.4%	-1.0 pts	28,435

Weighing up which year to buy? See the full ranking: Mercedes-Benz C years to avoid.

Buying a 2021 C? Two checks first

Free MOT history checkThe exact car’s failures, advisories and mileage trail — sellers can’t edit it
Topdon OBD2 scannersTopdon diagnostic scanners with full-system readouts
XTOOL diagnostic toolsXTOOL code readers for petrol and diesel cars
Autel UK testersAutel professional-grade diagnostic testers

FAQs

Is a 2021 Mercedes-Benz C reliable?

2021-registered examples passed 89.4% of their MOT tests (3,431 tests, 2023–2025), -1.0 points versus all UK cars registered in the same year. At roughly 5 years old with a median 28,435 miles, condition now varies car by car — always check the individual MOT history.

What mileage is too high for a 2021 C?

The median tested example shows 28,435 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.

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.