Mercedes-Benz 300 MOT pass rate: 81.7% (2,627 tests, 2025)

The Mercedes-Benz 300 passed 81.7% of its 2,627 MOT tests in 2025 — 4.2 points above the UK average of 77.5%. The median tested example was 36 years old with 104,728 miles on the clock.

81.7%Pass rate (2025)

2,627MOT tests analysed

104,728 miMedian mileage at test

36 yrsMedian age at test

How the 300 compares

Mercedes-Benz 300

81.7%

UK average (all Class 4 vehicles)

77.5% across 33.1 million tests

Mercedes-Benz average (all models)

80.7%

What fails most on the Mercedes-Benz 300

Across failed and rectified tests in 2025, these vehicle systems produced the most defects on the 300:

#	System	Defects recorded	Share
1	Lamps, reflectors and electrical equipment	390	26.3%
2	Brakes	313	21.1%
3	Suspension	255	17.2%
4	Body, chassis, structure	177	11.9%
5	Visibility	110	7.4%
6	Noise, emissions and leaks	104	7.0%

Pre-MOT checklist for 300 owners

Based on the failure profile above, ten minutes with a torch before your test removes the most likely fail items:

Walk round with all lights on: one blown bulb is the most avoidable fail there is
Feel for a spongy pedal or pulling to one side; check pad wear through the wheel spokes if visible
Bounce each corner and listen for clonks over speed bumps — suspension is this model’s (and the UK’s) top failure system
Look underneath for corrosion around sills and subframes, especially on older cars
Replace smeared wiper blades and top up washer fluid — both are test items

Check the engine before the tester does

A stored fault code with the engine light on is an automatic Major defect. Scan and clear resolved faults before booking.

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

Check a specific 300 before you buy

Pass rates describe the model; they can’t tell you about the one car you’re looking at. Run its plate through our free MOT history check to see its personal record of failures, advisories and mileage readings.

Other Mercedes-Benz models

C78.2% pass rate · 343,551 tests A-Class77.8% pass rate · 232,671 tests E79.7% pass rate · 215,896 tests A89.1% pass rate · 93,733 tests Vito73.4% pass rate · 81,263 tests GLC87.2% pass rate · 65,847 tests GLA83.1% pass rate · 64,404 tests CLA82.7% pass rate · 62,279 tests

FAQs

What is the MOT pass rate for a Mercedes-Benz 300?

In 2025, 81.7% of 2,627 first MOT tests on the Mercedes-Benz 300 were passes (UK average: 77.5%). Data: DVSA anonymised MOT results.

What does the 300 fail its MOT on most?

The biggest defect group is lamps, reflectors and electrical equipment (26.3% of its recorded defects), followed by brakes.

Is the Mercedes-Benz 300 reliable?

MOT pass rate is one lens on durability: at 81.7% it performs above the national average at a median age of 36 years and 104,728 miles. Always check the individual car's history too.

Source: DVSA Anonymised MOT tests and results, 2025 extract (Class 4 initial tests only; retests excluded). Contains public sector information licensed under the Open Government Licence v3.0. Figures rounded to one decimal place.