Diesel Mercedes-Benz C 320: MOT pass rate

70.3% of diesel Mercedes-Benz C 320s pass the MOT first time, measured across 728 DVSA tests on that fuel type alone. Average mileage at test was 122,371.

Diesel against the other Mercedes-Benz C 320 versions

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 C 320 specifically, diesel is the strongest at 70.3%, and this diesel version sits 0.3 points above the 70% 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 C 320 had covered 122,371 miles at test, against 105,049 for the petrol. That is high mileage, so timing belts, clutches, suspension bushes and corrosion are the items worth budgeting for rather than the MOT itself.

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 C 320 page separate age from fuel if you want to isolate one.

Most common MOT failures on a diesel Mercedes-Benz C 320

1. Smoke opacity levels exceed the manufacturer's specified limit, 2% of tests (7.52x the national rate for this defect)
2. Brake pipe damaged or excessively corroded, 6.3% of tests (5.91x the national rate for this defect)
3. A direction indicator lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning, 3.1% of tests (4.72x the national rate for this defect)
4. A suspension pin, bush or joint excessively worn, 14.7% of tests (2.92x the national rate for this defect)
5. Engine MIL illuminated indicating a malfunction, 3.2% of tests (2.52x the national rate for this defect)
6. A spring or spring component fractured or seriously weakened, 5.5% of tests (2.42x the national rate for this defect)
7. A suspension joint dust cover missing or no longer prevents the ingress of dirt etc, 4.2% of tests (2.26x the national rate for this defect)
8. Significant brake effort recorded with no brake applied indicating a binding brake, 2.3% of tests (2.2x the national rate for this defect)
9. A tyre cords visible or damaged, 3.4% of tests (2x the national rate for this defect)
10. Parking brake efficiency below minimum requirement, 2.6% of tests (1.96x the national rate for this defect)

From 744 DVSA-tracked diesel Mercedes-Benz C 320 tests, 2024, split out from the Mercedes-Benz C 320's other fuel types. DVSA testers marked 4.83% 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 C 320

Flagged but doesn't fail the car, a different list from the failures above.

1. A wheel bearing with excessive play, 6% of tests (9.32x the national rate for this defect)
2. A flexible brake hose excessively damaged, deteriorated, chafed, twisted or stretched, 3.5% of tests (6.24x the national rate for this defect)
3. Brake pipe damaged or excessively corroded, 33.9% of tests (5.47x the national rate for this defect), also fails
4. Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users, 13.2% of tests (2.37x the national rate for this defect)
5. A spring or spring component fractured or seriously weakened, 10.9% of tests (2.3x the national rate for this defect), also fails
6. A suspension component excessively damaged or corroded, 10.5% of tests (2.03x the national rate for this defect)
7. A suspension pin, bush or joint excessively worn, 26.2% of tests (1.96x the national rate for this defect), also fails
8. Tyre tread depth not in accordance with the requirements, 35.1% of tests (1.32x the national rate for this defect)
9. Brake disc or drum significantly and obviously worn, 4.2% of tests (1.31x the national rate for this defect)
10. Brake disc or drum excessively weakened, insecure or fractured, 12.8% of tests

From 744 DVSA-tracked diesel Mercedes-Benz C 320 tests, 2024.

Other Mercedes-Benz C 320 fuel types

• Petrol Mercedes-Benz C 320 - 69.4%

All Mercedes-Benz C 320 MOT data · Every model