Mercedes-Benz S-Class MOT failure rate and common faults

22,917 Mercedes-Benz S-Class cars aged 3 to 20 took their MOT in 2025, and 15.4% failed at the first attempt. An average car of the same age failed 28.0% of the time, which makes the Mercedes-Benz S-Class 45% less likely to fail than the typical car on the road. Here is what fails, and which years to look for.

15.4%

failed first time

22,917 MOT tests in 2025

-45%

vs same age average

average car of this age mix: 28.0%

5 of 208

age adjusted rank

among cars; 1 fails least

80.6

dangerous defects per 1,000

same age average: 104.1

What fails on a Mercedes-Benz S-Class MOT

Failure items recorded per 1,000 tests, by part of the car, set against an average car with exactly the same spread of ages. A figure well above average is a weak spot worth checking before you buy.

Tyres71 19% below average
Brakes63 38% below average
Suspension62 54% below average
Lights and electrics34 79% below average
Engine, emissions and leaks29 26% below average
Windscreen, wipers and mirrors24 52% below average
Wheels11 2.0x average
Body, chassis, exhaust and drive shafts7 84% below average
Number plates and VIN6 1.5x average
Seat belts and airbags6 47% below average
Steering4 83% below average

The most common Mercedes-Benz S-Class MOT failures

The individual failure items testers recorded most often, per 1,000 tests.

Failure itemAreaPer 1,000 tests
Ball joint excessively wornSuspension34.0
Tread depth below requirements of 1.6mmTyres24.1
Malfunction indicator lamp: inoperative or indicates a malfunctionEngine, emissions and leaks17.8
Tyres: has ply or cords exposedTyres14.4
Tyres: has a cut in excess of the requirements deep enough to reach the ply or cordsTyres12.7
Suspension arms: pin or bush excessively wornSuspension8.9
Brake pads: less than 1.5 mm thickBrakes8.6
Parking brake efficiency: efficiency below requirementsBrakes8.0
Rigid brake pipes: excessively corrodedBrakes8.0
Washers: provides insufficient washer liquidWindscreen, wipers and mirrors7.8
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Mercedes-Benz S-Class MOT failure rate by year

Every car fails more often as it ages, so each registration year is compared with the average for all cars of the same age. Years with fewer than 500 tests are left out.

First registeredTestsFailedSame age averageAverage mileage
20227247.3%11.4%46,100
202168410.4%12.8%47,800
20206567.8%14.1%63,000
20192,3069.5%16.5%78,200
20182,1849.5%19.1%80,600
20172,27112.8%21.8%80,400
20162,63414.3%25.1%82,200
20152,12413.1%28.1%94,400
20141,58212.3%31.4%102,400
201394518.2%34.3%112,400
20121,14819.7%36.6%108,100
201188821.6%38.8%113,400
201077421.8%40.7%112,300
200975327.9%41.8%113,400
200881427.1%42.9%113,000
20071,12524.3%42.7%115,200
200688122.3%43.0%110,200

Advisories to look for in a Mercedes-Benz S-Class's MOT history

An advisory is a tester's warning that something is wearing but has not failed yet. These are the ones written most often on the Mercedes-Benz S-Class, per 1,000 tests. If the car you are looking at has one of these, ask whether it has been fixed since.

  • Tread depth: worn close to legal limit/worn on edge254.7
  • Brake discs: worn, pitted or scored, but not seriously weakened96.3
  • Rigid brake pipes: corroded, covered in grease or other material79.2
  • Brake pads: wearing thin72.3
  • Ball joint has slight play70.8
  • Brake discs: worn, but not excessively45.1

Checking a used Mercedes-Benz S-Class before you buy

Against cars of the same age, the Mercedes-Benz S-Class fails more often than average on wheels. Start there.

  • Wheels

    Look for damaged rims, missing wheel nuts and cracked alloys, particularly on the inside edge where kerb damage hides.

Averages only take you so far. The specific car's MOT history shows whether it has already failed on any of these, how often advisories were ignored, and whether the mileage climbs steadily from test to test. Read our guide to reading a car's MOT history before you go to view it.

Fuel mix of the Mercedes-Benz S-Class cars tested: Diesel 73%, Petrol 19%, Hybrid 7%. Average age at test 10.5 years, average recorded mileage 91,600.

Mercedes-Benz S-Class MOT questions

What is the Mercedes-Benz S-Class MOT failure rate?

15.4% of Mercedes-Benz S-Class cars failed their first MOT test of 2025, from 22,917 tests on vehicles aged 3 to 20. An average car with the same age mix failed 28.0% of the time, so the Mercedes-Benz S-Class was 45% less likely to fail.

What fails most often on a Mercedes-Benz S-Class MOT?

Tyres caused the most failure items, at 71 per 1,000 tests. The single most common failure item was "Ball joint excessively worn", recorded 34.0 times per 1,000 tests.

Which Mercedes-Benz S-Class year has the best MOT record?

Measured against cars of the same age, 2014 registrations did best: 12.3% failed against an average of 31.4% for cars that age. Older cars always fail more often, so compare a year with its age group rather than with newer cars.

Does this tell me whether a particular Mercedes-Benz S-Class will pass?

No. These are averages across every Mercedes-Benz S-Class tested in 2025. The car in front of you has its own record: its full MOT history shows every pass, failure and advisory it has had, and it is free to view by registration.

Other Mercedes-Benz models

Ranked close to the Mercedes-Benz S-Class

How these figures are calculated

Source: DVSA Anonymised MOT tests and results, 2025 release. We count first tests of cars and small vans (class 4) aged 3 to 20, so a car that fails and is retested is counted once. A failure includes faults fixed and passed within the same visit. The same age average weights the national failure rate for each age by how many Mercedes-Benz S-Class cars of that age were tested, so a model is never penalised for having an older fleet. Make and model are as recorded at the test; trim levels are combined. Full method and rankings.

Contains public sector information licensed under the Open Government Licence v3.0.