Diesel Mercedes-Benz S-Class: MOT pass rate

85.2% of diesel Mercedes-Benz S-Class pass the MOT first time, measured across 17,692 DVSA tests on that fuel type alone. Average mileage at test was 99,135.

Diesel against the other Mercedes-Benz S-Class 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 S-Class specifically, hybrid is the strongest at 90.2%, and this diesel version sits 0 points above the 85.2% 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 S-Class had covered 99,135 miles at test, against 81,126 for the petrol and 68,241 for the hybrid. That is above average and into the range where cambelts and water pumps are due if they have not already been done, so ask for the service history rather than take the mileage on trust.

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 S-Class page separate age from fuel if you want to isolate one.

Most common MOT failures on a diesel Mercedes-Benz S-Class

1. Any fracture or welding defect on a wheel, 0.6% of tests (10.59x the national rate for this defect)
2. Smoke opacity levels exceed the manufacturer's specified limit, 0.8% of tests (2.97x the national rate for this defect)
3. Parking brake efficiency less than 50% of the required value, 0.6% of tests (1.65x the national rate for this defect)
4. Brake pipe damaged or excessively corroded, 1.3% of tests (1.2x the national rate for this defect)
5. A suspension pin, bush or joint excessively worn, 5.1% of tests
6. Tyre tread depth not in accordance with the requirements, 3.5% of tests
7. A tyre seriously damaged, 2.1% of tests
8. A tyre cords visible or damaged, 1.6% of tests
9. Engine MIL illuminated indicating a malfunction, 1.5% of tests
10. Windscreen washers not working or not providing sufficient fluid to clear the windscreen, 1% of tests

From 17,812 DVSA-tracked diesel Mercedes-Benz S-Class tests, 2024, split out from the Mercedes-Benz S-Class's other fuel types. DVSA testers marked 6.67% 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 S-Class

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

1. A transmission shaft flexible coupling excessively deteriorated, 0.8% of tests (12.23x the national rate for this defect)
2. A wheel bearing with excessive play, 4% of tests (6.15x the national rate for this defect)
3. Brake pipe damaged or excessively corroded, 10.5% of tests (1.7x the national rate for this defect), also fails
4. A flexible brake hose excessively damaged, deteriorated, chafed, twisted or stretched, 0.9% of tests (1.69x the national rate for this defect)
5. Brake disc or drum significantly and obviously worn, 4.6% of tests (1.46x the national rate for this defect)
6. Tyre tread depth not in accordance with the requirements, 28.8% of tests, also fails
7. A suspension pin, bush or joint excessively worn, 11.1% of tests, also fails
8. Brake disc or drum excessively weakened, insecure or fractured, 9.9% of tests
9. a brake lining or pad worn below 1.5mm, 7.4% of tests
10. A tyre seriously damaged, 6.3% of tests, also fails

From 17,812 DVSA-tracked diesel Mercedes-Benz S-Class tests, 2024.

Other Mercedes-Benz S-Class fuel types

• Petrol Mercedes-Benz S-Class - 84.8%
• Hybrid Mercedes-Benz S-Class - 90.2%

All Mercedes-Benz S-Class MOT data · Every model