Mercedes-Benz SLK MOT failure rate and common faults
42,227 Mercedes-Benz SLK cars aged 3 to 20 took their MOT in 2025, and 27.4% failed at the first attempt. An average car of the same age failed 37.1% of the time, which makes the Mercedes-Benz SLK 26% less likely to fail than the typical car on the road. Here is what fails, and which years to look for.
27.4%
failed first time
42,227 MOT tests in 2025
-26%
vs same age average
average car of this age mix: 37.1%
32 of 208
age adjusted rank
among cars; 1 fails least
100.3
dangerous defects per 1,000
same age average: 128.9
What fails on a Mercedes-Benz SLK 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.
The most common Mercedes-Benz SLK MOT failures
The individual failure items testers recorded most often, per 1,000 tests.
| Failure item | Area | Per 1,000 tests |
|---|---|---|
| Coil spring: fractured or broken | Suspension | 64.4 |
| Ball joint excessively worn | Suspension | 38.3 |
| Tread depth below requirements of 1.6mm | Tyres | 29.9 |
| Tyres: has ply or cords exposed | Tyres | 22.9 |
| Rigid brake pipes: excessively corroded | Brakes | 21.5 |
| Ball joint dust cover no longer prevents the ingress of dirt | Suspension | 18.7 |
| Linkage ball joint dust cover: ball joint dust cover no longer prevents the ingress of dirt | Suspension | 18.0 |
| Tyres: has a cut in excess of the requirements deep enough to reach the ply or cords | Tyres | 17.6 |
| Suspension arms: pin or bush excessively worn | Suspension | 16.8 |
| Malfunction indicator lamp: inoperative or indicates a malfunction | Engine, emissions and leaks | 16.4 |
Mercedes-Benz SLK 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 registered | Tests | Failed | Same age average | Average mileage |
|---|---|---|---|---|
| 2016 | 1,249 | 17.7% | 25.1% | 46,000 |
| 2015 | 4,848 | 20.0% | 28.1% | 51,800 |
| 2014 | 4,791 | 23.6% | 31.4% | 58,600 |
| 2013 | 4,488 | 25.7% | 34.3% | 65,900 |
| 2012 | 5,481 | 26.3% | 36.6% | 66,900 |
| 2011 | 2,486 | 24.7% | 38.8% | 63,500 |
| 2010 | 2,031 | 29.4% | 40.7% | 68,800 |
| 2009 | 2,449 | 30.7% | 41.8% | 71,400 |
| 2008 | 3,115 | 32.1% | 42.9% | 76,800 |
| 2007 | 3,389 | 32.7% | 42.7% | 77,600 |
| 2006 | 3,473 | 33.0% | 43.0% | 80,800 |
| 2005 | 4,421 | 32.1% | 42.4% | 82,200 |
Advisories to look for in a Mercedes-Benz SLK'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 SLK, 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 edge251.0
- Rigid brake pipes: corroded, covered in grease or other material158.7
- Brake discs: worn, pitted or scored, but not seriously weakened126.8
- Tyres: slightly damaged/cracking or perishing121.7
- Suspension arms: pin or bush worn but not resulting in excessive movement80.2
- Brake pads: wearing thin57.5
Checking a used Mercedes-Benz SLK before you buy
The Mercedes-Benz SLK has no part of the car that fails well above average for its age, so check the areas that fail most often overall.
Suspension
Drive over speed bumps with the radio off and listen for knocks. Look at the car side on: a corner sitting lower than the others often means a broken coil spring.
Tyres
Check the tread across the full width of every tyre, inner edge included. Uneven wear points to worn suspension or out of line steering geometry.
Brakes
Look through the wheel spokes at the discs for a deep lip or scoring, check the handbrake holds the car on a slope, and feel for a pull to one side when braking hard.
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 SLK cars tested: Petrol 69%, Diesel 31%. Average age at test 14.5 years, average recorded mileage 68,000.
Mercedes-Benz SLK MOT questions
What is the Mercedes-Benz SLK MOT failure rate?
27.4% of Mercedes-Benz SLK cars failed their first MOT test of 2025, from 42,227 tests on vehicles aged 3 to 20. An average car with the same age mix failed 37.1% of the time, so the Mercedes-Benz SLK was 26% less likely to fail.
What fails most often on a Mercedes-Benz SLK MOT?
Suspension caused the most failure items, at 199 per 1,000 tests. The single most common failure item was "Coil spring: fractured or broken", recorded 64.4 times per 1,000 tests.
Which Mercedes-Benz SLK year has the best MOT record?
Measured against cars of the same age, 2011 registrations did best: 24.7% failed against an average of 38.8% 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 SLK will pass?
No. These are averages across every Mercedes-Benz SLK 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
- Mercedes-Benz A-Class21.5% failed
- Mercedes-Benz C-Class24.8% failed
- Mercedes-Benz E-Class22.3% failed
- Mercedes-Benz GLA16.8% failed
- Mercedes-Benz GLC13.7% failed
- Mercedes-Benz Vito32.5% failed
Ranked close to the Mercedes-Benz SLK
- SEAT Atecarank 29
- Suzuki Celeriorank 30
- Skoda Karoqrank 31
- BMW 4 Seriesrank 33
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 SLK 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.