Mercedes-Benz 300 MOT pass rate and common failures
In 2025, 78.2% of Mercedes-Benz 300 MOT tests were a first-time pass, across 2,634 tests in Great Britain. For all cars it was 71.5%.
Compared with cars of the same age
Older cars fail more often, so a model that’s mostly a few years old will look better than one that’s mostly 12. These figures compare like with like.
At 3–5 years
–
Too few tests at this age to say.
At 6–10 years
–
Too few tests at this age to say.
At 11 years and over
78.2%
All cars: 61.3% (16.9 points better). 2,581 tests.
Figures by age, with typical mileage
| Age (years) | Tests | First-time pass | All cars | Typical mileage |
|---|---|---|---|---|
| 20+ | 2,581 | 78.2% | 61.4% | 103,750 miles |
Typical mileage is the median reading at the test, to the nearest 2,500 miles.
What fails most often
The share of Mercedes-Benz 300 MOT tests that failed on at least one item in each area, against all cars. A test can fail on several areas at once.
| Area | 300 | All cars |
|---|---|---|
| Lamps, reflectors and electrical equipment | 18.0% | 16.6% |
| Brakes | 11.7% | 10.2% |
| Suspension | 9.4% | 13.7% |
| Body, chassis, structure | 6.6% | 4.2% |
| Visibility | 4.9% | 5.2% |
| Noise, emissions and leaks | 3.9% | 4.0% |
| Steering | 2.7% | 2.5% |
| Tyres | 2.5% | 8.4% |
Most common reasons for failing
- Headlamp aim: too low failed 2.8% of tests · what this means
- Component mounting prescribed areas: prescribed area excessively corroded significantly reducing structural strength failed 2.3% of tests
- Position lamp: not working failed 2.3% of tests · what this means
- Ball joint dust cover no longer prevents the ingress of dirt failed 2.2% of tests · what this means
- Wipers: does not clear the windscreen effectively failed 1.8% of tests · what this means
- Rear fog lamp: not working failed 1.6% of tests · what this means
- Non catalyst emissions: emissions carbon monoxide content excessive failed 1.5% of tests · what this means
- Service brake performance: excessively binding failed 1.4% of tests · what this means
- Washers: provides insufficient washer liquid failed 1.4% of tests · what this means
- Headlamp aim: too high failed 1.2% of tests · what this means
Checking a particular 300?
See its own MOT history, mileage record and advisories in plain English. Free, no sign-up.
About these figures
- They cover every 300 version DVSA records under this name (engines, trims and generations together), on its first MOT test of each visit. A “pass with rectification” (fixed within an hour) counts as a fail, as in DVSA’s own statistics.
- Cars under three years old are left out, because the few tested that young are mostly taxis.
- Fuel mix of the cars tested: petrol 82.5%, diesel 17.0%, electric diesel 0.3%.
- A pass rate describes the model, not any one car. How a car has been looked after matters more.
Download these figures (CSV) · Other Mercedes-Benz models · All makes
Source: DVSA anonymised MOT test data for 2025. Contains public sector information licensed under the Open Government Licence v3.0. Our own analysis; not produced or endorsed by DVSA.