2021 Mercedes-Benz C300 MOT pass rate

2021
typical 20,072 mi

Pass rate

88.8%

Above average — 2.4 pts behind the 91.2% that cars this age and mileage manage.

Across 187 recorded tests.

Typical repair bill £45–£101

Most common fault

Tyres

61.4% of faults · 19.8% nationally

mostly tread below the limit, cuts and sidewall bulges.

Part only £55–£85 for Tread depth below 1.6 mm. What fitting it takes →

Every failure, with what it costs →

Which year to buy

Best 2022 90.9% pass
Avoid 2021 88.8% pass · this year

Across the 2 years on record, a spread of 2.1 points. See every year →

First-attempt pass: 87.4%
Typical mileage: 20k mi

The 2021 Mercedes-Benz C300 MOT pass rate is 88.8% of its MOT tests — 2.4 points behind what its age and mileage predict. Tyres is the biggest single reason it fails, at 61.4% of what testers record.

Check your postcode

MOT pass rates are national — type your postcode to see how Mercedes-Benz C300 does in your corner of the country.

How one model's pass rate varies by postcode →

Expert verdict

Tyres: 3.1× the national share

Tyres make up 61.4% of everything recorded on the 2021 Mercedes-Benz C300, against 19.8% nationally — 41.6 points above. Check all four tyres yourself, including the inner shoulders, and look at the date stamp — a tyre can pass on tread and still be six years old.

When it fails, it costs. Only 0% of this model’s typical repairs come in under £30 in parts — the failures here tend to be the kind that need a garage rather than a bulb.
Based on a small sample. 187 tests back this page. That is enough to publish and to index, not enough to treat the decimal places as precise — read the pattern, not the second digit.

Written from this page's own figures: fault shares against the national composition, the like-for-like pass rate, and the priced repair list. How these are worked out

How does the 2021 Mercedes-Benz C300 compare?

Cars of this age and mileage average 91.2%, so this figure is 2.4 points behind what its age and mileage predict. On a first attempt, before any retests, the figure drops to 87.4%. The median 2021 Mercedes-Benz C300 in this dataset had covered 20,072 mi.

Pass rates also shift with the test month: tests recorded October–March passed 85.7% of the time, April–September 91.7%.

The single most recorded failure item is "Fractured", noted on 2.67% of tests.

187 recorded tests behind this page.
88.8% overall pass rate, 87.4% on a first attempt.
Across every year of the Mercedes-Benz C300, the average is 89.3% — best year 2022 (90.9%), worst 2021 (88.8%).

Figures count every completed test on this vehicle-year in the dataset, including retests. See methodology for the exact definition.

This page's data

Tests analysed: 187
Typical mileage (median): 20,072 mi
Make and model: Mercedes-Benz C300
Updated: 2026-11-05

Source: DVSA anonymised MOT test data (2023–2025), OGL v3.0.

Top part to budget for

Wheel Hub Bearing Kit

Usually a DIY or independent-garage job.

Does mileage affect the C300 MOT pass rate?

0-30k 90.7%

30-60k 82.2%

60-90k 100.0%

Pass rate by odometer reading. Bar lengths start at 74% so small gaps stay visible.

Regional pass rates for the C300

Region	Tests	Pass rate
South East	70	88.6%
South West	20	95.0%
Yorkshire	15	93.3%
London	15	93.3%
North West	15	93.3%

Regions come from the postcode area recorded at the test station. Areas on region borders are assigned to the region with the majority of their population.

What fails a 2021 C300

Everything a tester recorded on this vehicle, grouped into the inspection sections that produced it. The notch on each bar is the national share, so you can see at a glance whether this car is unusual or just ordinary.

Tyres 61.4%

+41.6 pts vs national national 19.8% Compare tyre prices

Visibility 8.4%

+3.4 pts vs national national 5.0% Order bulbs & wipers

Road wheels 7.2%

+6.5 pts vs national national 0.8% Price road wheels parts

Lamps & electrics 6.0%

−6.2 pts vs national national 12.2% Order bulbs & wipers

Show the other 5 fault categories

Brakes 4.8%
Body & chassis 4.8%
Advisories 4.8%
Suspension 1.2%
Emissions & leaks 1.2%

Shares are of every item recorded on 2021 Mercedes-Benz C300 tests — a composition, so they add to 100% across all sections, not per test.

A test can record several items, so these percentages do not add up to 100%. The exact strings, with prices, are in the full DVSA record at the bottom of this page.

Before your test

Three checks worth doing on a 2021 C300

These are not generic tips — they are the faults recorded most often on this exact model, rewritten as things you can check yourself. All three take about ten minutes and cost nothing.

Check the windscreen 2.1% of tests

“windscreen damaged”

Check the driver’s side of the screen within the swept area for chips and cracks; anything larger than 10mm in the driver’s central view is a fail. Most chips can be resin-repaired for far less than a new screen.
Check the tyre tread 1.6% of tests

“tread depth below requirements of 1.6mm”

Check all four tyres cold, including the inner shoulder where wear hides — 1.6mm across the central three-quarters is the legal limit, and most testers fail at 1.6mm without argument.
Check the lights 1.1% of tests

“headlamp aim too high”

Switch everything on and walk round the car: both headlamps on dip and main, every indicator, both brake lights, reverse, fog and the two number-plate lamps. A bulb is a few pounds and a five-minute job.

What testers look for →

Shares are the proportion of tests on this vehicle that recorded the item, so they overlap: one test can record several.

What it costs to get a 2021 C300 through its MOT

Across the 10 items that are recorded most often on this model, the average repair comes to £45–£101 — and 0% of those repairs are parts that cost under £30.

Average repair across the 10 common items: £45–£101
Cheapest common item: fractured: £20–£55
Dearest common item: windscreen damaged: £80–£200
Common items a careful owner can do at home: 80%
Repairs that still cost under £30: 0%

Estimates from typical UK parts prices, weighted by how often each item appears in 187 MOT tests on this vehicle. They exclude diagnostics, retest fees and garage labour where the part is a DIY fit, and they are not figures from the DVSA dataset. Older and higher-mileage examples cost more than the average. How these estimates are built → · All MOT repair costs → · Cheapest cars to put through a test →

Every year of the C300, side by side

2 model years on record, from 2021 to 2022. Across them the pass rate runs from 88.8% to 90.9% — a spread of 2.1 points. The bar under each year is the item that failed it most often.

2021 88.8%
fractured
2022 90.9% fractured

Colour is the pass rate on a fixed scale, so a block means the same thing on any model. Each year links to its own page with the full fault breakdown.

Compare the 2021 Mercedes-Benz C300 with another year

The raw pass rate mostly measures age. The year comparison adds the like-for-like figure, the mileage bands and the repair bill.

Compare 2021 with another year →

Compare two different cars instead →

Other 2021 cars with a similar record

Closest pass rates among 2021 cars with at least 2,000 tests, so a small sample cannot flatter itself into the list. See the full rankings: best and worst MOT pass rates.

The full DVSA record for the 2021 Mercedes-Benz C300 10 failure items · 6 advisories · 9 inspection categories · mileage brackets · all of it in the page, none of it above the fold

Every inspection category

Shares of the 83 individual items recorded on this vehicle, and the same share across all cars nationally. A single test can record several items, so a row is not a percentage of tests.

Category	Items	This car	Nationally	Difference
Tyres	51	61.40%	19.76%	+41.64
Visibility	7	8.40%	4.97%	+3.43
Road Wheels	6	7.20%	0.75%	+6.45
Lamps, reflectors and electrical equipment	5	6.00%	12.21%	−6.21
Brakes	4	4.80%	20.89%	−16.09
Body, chassis, structure	4	4.80%	5.57%	−0.77
Non-component advisories	4	4.80%	4.18%	+0.62
Suspension	1	1.20%	20.98%	−19.78
Noise, emissions and leaks	1	1.20%	5.52%	−4.32

The exact failure items, in the tester's words

Share of the 187 tests on this vehicle that recorded each item
Recorded item	Severity	Tests	Est. cost	Part
Fractured Road Wheels	Major	2.7%	£20–55	Wheel Hub Bearing Kit →
Has a bulge, caused by separation or partial failure of its structure Tyres	Major	2.7%	£45–95	Tyres →
Has a cut in excess of the requirements deep enough to reach the ply or cords Tyres	Major	2.7%	£45–95	Tyres →
Windscreen damaged but not adversely affecting driver's view Visibility	Minor	2.1%	£80–200	Windscreen →
Has a lump, caused by separation or partial failure of its structure Tyres	Major	1.6%	£45–95	Tyres →
Has ply or cords exposed Tyres	Major	1.6%	£45–95	Tyres →
Tread depth below requirements of 1.6mm Tyres	Major	1.6%	£45–95	Tyres →
Has a tear, caused by separation or partial failure of its structure Tyres	Major	1.1%	£45–95	Tyres →
Headlamp aim too high Lamps, reflectors and electrical equipment	Rectified	1.1%	£30–80	Headlight Alignment →
Has ply or cords damaged Tyres	Major	0.53%	£45–95	Tyres →

Severity is as recorded: Major and Dangerous fail the test outright; Minor and Advisory do not. Costs are estimates from typical UK parts prices — see how they are built.

What testers noted without failing the car

Advisories are the early warnings — the same parts a year or two before they fail. Reading them is how you tell a car that has been maintained from one that has been patched.

Items recorded as advisory on this vehicle
Recorded item	Severity	Tests	Est. cost
Tread depth below requirements of 1.6mm Tyres	Advisory	10.7%	£45–95
Brake pads less than 1.5 mm thick Brakes	Advisory	2.1%	£18–45
Flexible couplings excessively deteriorated Body, chassis, structure	Advisory	2.1%	£80–250
Has a cut in excess of the requirements deep enough to reach the ply or cords Tyres	Advisory	2.1%	£45–95
Non-component advisories Nail in tyre Non-component advisories	Advisory	2.1%	£45–95
Has a tear, caused by separation or partial failure of its structure Tyres	Advisory	1.6%	£45–95

Pass rate by mileage

Mileage	Tests	Pass rate	Median odometer
0-30k	140	90.7%	16,469 mi
30-60k	45	82.2%	39,412 mi
60-90k	2	100.0%	61,468 mi

Source: 187 recorded tests on this vehicle-year. Every row above is recomputed from the same DVSA extract as the rest of the page — see the methodology.

2021 C300 MOT questions

What is the MOT pass rate for a 2021 Mercedes-Benz C300?

88.8% of the 187 2021 Mercedes-Benz C300 tests in this dataset passed, against a national average of 91.2% for cars first used in 2021. First-attempt pass rate: 87.4%.

What are the most common MOT failures on a 2021 Mercedes-Benz C300?

The three most recorded items are fractured (2.67%), has a bulge, caused by separation or partial failure of its structure (2.67%), has a cut in excess of the requirements deep enough to reach the ply or cords (2.67%). Percentages are the share of tests on this vehicle that recorded the item.

Does mileage affect the 2021 Mercedes-Benz C300 MOT pass rate?

Yes. Cars under 30,000 miles passed 90.7% of the time, falling to 100.0% for those over 120,000 miles. The median 2021 Mercedes-Benz C300 in this dataset had covered 20,072 mi.

Does the season affect the 2021 Mercedes-Benz C300 MOT pass rate?

Tests recorded in the winter months (October–March) passed 85.7% of the time; summer months (April–September) passed 91.7%. Brakes, tyres and lights are tested harder in bad weather, but the difference is small on most models.