Diesel Mercedes-Benz B: MOT pass rate
91.5% of diesel Mercedes-Benz Bs pass the MOT first time, measured across 3,098 DVSA tests on that fuel type alone. Average mileage at test was 30,697.
Diesel against the other Mercedes-Benz B versions
| Fuel | Pass rate | Tests |
|---|---|---|
| Petrol | 92.6% | 4,792 |
| Diesel | 91.5% | 3,098 |
| All Mercedes-Benz B | 92.2% | 7,891 |
Why the fuel type changes the number
Diesels carry DPFs, EGR valves and stricter smoke limits, so emissions and exhaust faults account for failures petrol cars never see.
On the Mercedes-Benz B specifically, petrol is the strongest at 92.6%, and this diesel version sits 0.7 points below the 92.2% model average.
What it means if you are buying one
There is little to choose between fuel types on this model, so decide on running costs and mileage rather than MOT record. Buying a damaged one? run it through the analyzer, check the exact car, decode the VIN and check the mileage before you bid.
Mileage is part of the answer
The average diesel Mercedes-Benz B had covered 30,697 miles at test, against 25,056 for the petrol. That is below average for a car this age, worth a mileage-consistency check since an unusually low reading is sometimes clocking rather than luck.
Fuel type and mileage are tangled together: diesels are usually bought by higher-mileage drivers, so some of any gap between fuels is the miles rather than the engine. The per-year figures on the Mercedes-Benz B page separate age from fuel if you want to isolate one.
Most common MOT failures on a diesel Mercedes-Benz B
- A tyre seriously damaged, 3.5% of tests (1.24x the national rate for this defect)
- An SRS malfunction indicator lamp (MIL) indicates a system malfunction, 0.5% of tests (1.16x the national rate for this defect)
- Tyre tread depth not in accordance with the requirements, 1.3% of tests
- A tyre cords visible or damaged, 1.3% of tests
- a brake lining or pad worn below 1.5mm, 1.1% of tests
- Wiper blade missing or obviously not clearing the windscreen, 0.6% of tests
- Engine MIL illuminated indicating a malfunction, 0.4% of tests
- A suspension pin, bush or joint excessively worn, 0.4% of tests
- The aim of a headlamp is not within limits laid down in the requirements, 0.4% of tests
- Windscreen washers not working or not providing sufficient fluid to clear the windscreen, 0.4% of tests
From 3,112 DVSA-tracked diesel Mercedes-Benz B tests, 2024, split out from the Mercedes-Benz B's other fuel types. DVSA testers marked 6.33% of these flagged defects as "dangerous", against 5.11% nationally. See which fuel type fails on the most dangerous defects nationally for how that compares across the whole fleet.
Most common MOT advisories on a diesel Mercedes-Benz B
Flagged but doesn't fail the car, a different list from the failures above.
- Tyre tread depth not in accordance with the requirements, 21.5% of tests, also fails
- A tyre seriously damaged, 16.1% of tests, also fails
- a brake lining or pad worn below 1.5mm, 6.6% of tests, also fails
- Brake disc or drum excessively weakened, insecure or fractured, 3.9% of tests
- A suspension pin, bush or joint excessively worn, 3.5% of tests, also fails
- Brake disc or drum significantly and obviously worn, 3% of tests
- Number plate inscription missing or illegible, 0.5% of tests
- A wheel bearing with excessive play, 0.4% of tests
- A wheel badly distorted or wear between wheel and hub at spigot mounting, 0.4% of tests
- Significant brake effort recorded with no brake applied indicating a binding brake, 0.3% of tests
From 3,112 DVSA-tracked diesel Mercedes-Benz B tests, 2024.
Other Mercedes-Benz B fuel types
- Petrol Mercedes-Benz B - 92.6%