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Mercedes-Benz 300 common problems and MOT pass rate

In 2025, DVSA recorded 2,653 initial MOT tests on the Mercedes-Benz 300 in Great Britain, and 78.3% passed first time. Here is where the rest failed.

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Mercedes-Benz 300 at the MOT, 2025

Initial MOT tests
2,653
Passed first timeAll cars and vans: 72.1%
78.3%
Failed at firstIncluding 3.5% repaired at the test and passed (PRS)
21.7%
Had a dangerous defectAll cars and vans: 7.3%
4.0%
Licensed in the UKEnd of 2026 Q2, plus 5,443 off the road (SORN)
2,880

Contains DVSA MOT data, Open Government Licence v3.0, year 2025.

Failure areas

Where the 300 fails its MOT

The share of initial tests in 2025 with at least one fail or PRS item in each part of the MOT. A test can fail in more than one area, so these do not add up to the fail rate.

  1. 1Lamps, reflectors and electrical equipment

    10.5%

    Headlamps and their aim, brake lights, indicators, fog and reversing lamps, warning lights, battery and wiringAll cars and vans: 10.8%

  2. 2Brakes

    6.9%

    Pedal and handbrake, pipes and hoses, discs, pads and drums, and how well the car stopsAll cars and vans: 6.4%

  3. 3Suspension

    6.0%

    Springs, shock absorbers, suspension arms and bushes, anti-roll bars, wheel bearings and axlesAll cars and vans: 9.0%

  4. 4Body, chassis and structure

    4.7%

    Corrosion and damage to the structure, the exhaust system, fuel system, doors, seats, towbar, bumpers and engine mountingsAll cars and vans: 3.3%

  5. 5Visibility

    4.1%

    The driver's view, windscreen damage, wipers, washers and mirrorsAll cars and vans: 4.4%

  6. 6Noise, emissions and leaks

    3.5%

    Exhaust emissions and smoke, exhaust noise and fluid leaksAll cars and vans: 3.2%

  7. 7Steering

    2.0%

    Steering rack, joints and linkages, power steering, the steering wheel and columnAll cars and vans: 2.0%

  8. 8Tyres

    1.7%

    Tread depth, cuts and bulges, the right size and type, valves and tyre pressure warning systemsAll cars and vans: 6.2%

  9. 9Seat belts and airbags

    1.0%

    Seat belts, airbags and the airbag warning lightAll cars and vans: 1.0%

  10. 10Registration plates and VIN

    0.3%

    Number plates and the vehicle identification numberAll cars and vans: 0.3%

This modelAll cars and vans

Parts

The parts that fail most

Share of initial tests with a fail or PRS item on each part, 2025.

  1. Brake performanceBrakes4.3%
  2. Headlamp aimLamps and electrics3.7%
  3. Exhaust emissionsEmissions and leaks3.1%
  4. WashersVisibility2.4%
  5. Suspension armsSuspension2.3%
  6. Position lampsLamps and electrics2.1%
  7. WipersVisibility2.1%
  8. HeadlampsLamps and electrics2.0%

Checking a particular 300?

Averages tell you what to look at. The registration tells you about this car: every MOT since 2005 with its failures and advisories, each mileage reading, and whether it is taxed.

Questions

Mercedes-Benz 300: common questions

Contains DVSA MOT data, Open Government Licence v3.0, year 2025.

What is the most common MOT failure on the Mercedes-Benz 300?
In DVSA's 2025 test records, the area that failed most often on the Mercedes-Benz 300 was lamps, reflectors and electrical equipment: 10.5% of initial tests had at least one fail or PRS item there, against 10.8% for all cars and vans. Next came brakes (6.9%) and suspension (6.0%).
What is the MOT pass rate for the Mercedes-Benz 300?
78.3% of 2,653 initial MOT tests on the Mercedes-Benz 300 in 2025 were a pass first time. Another 3.5% passed after small repairs made at the test station within the hour (PRS). Across all cars and vans, 72.1% passed first time.
Does a lower pass rate mean the Mercedes-Benz 300 is unreliable?
Not on its own. MOT results depend on age, mileage and upkeep as much as on design, so a model with many older cars on the road will usually fail more often. The table by year compares cars of a similar age. What matters most is the record of the car you are looking at, so check its MOT history before you buy.
What counts as a dangerous defect?
One the tester judges to be a direct and immediate risk to road safety, or to have a serious impact on the environment. The car fails and should not be driven until it is repaired. 4.0% of initial tests on the Mercedes-Benz 300 found at least one, against 7.3% for all cars and vans.
Where do these figures come from?
From DVSA's anonymised MOT test data for 2025, published under the Open Government Licence. We count initial tests on cars and light vans in Great Britain, as DVSA does in its own statistics: retests, appeals and abandoned tests are left out, and so are advisories and minor defects.

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