71.9%
Mercedes-Benz SLK
Mercedes-Benz SLK MOT pass rate and common problems
The Mercedes-Benz SLK passed 71.9% of its initial MOT tests in 2025, 0.5 percentage points below the 72.3% UK average. The item testers recorded most often was coil spring fractured or broken.
Checking a specific car? Its own results, advisories and recorded mileages are in a free MOT history check.
How the SLK compares
Initial MOT tests in 2025, retests excluded. A car that failed and was repaired at the test station counts as a fail.
77.1%
Mercedes-Benz average
72.3%
UK average, all cars
The SLK runs 5.2 points behind the Mercedes-Benz average. It is 29th of the 35 Mercedes-Benz models in the data. The average SLK arrived at its test 16.5 years old with 71,783 miles recorded.
A pass rate records whether cars met the roadworthiness standard on test day. It is not a reliability score, and part of any gap reflects how old the tested cars were.
SLK MOT pass rate by age
The same 2025 tests split by the car's age at test.
Mercedes-Benz SLK cars aged 6 to 10 years passed 79.6% of MOT tests. For cars aged 11 years and over that fell to 70.4%, a drop of 9.2 percentage points.
| Age at test | Tests | Pass rate | vs UK average |
|---|---|---|---|
| 6 to 10 years | 8,509 | 79.6% | 7.3 pts above |
| 11 years and over | 45,667 | 70.4% | 1.9 pts below |
That is a typical decline as cars age. The UK average of 72.3% covers cars of every age, so compare like with like.
Where SLK failures cluster
Every failure item recorded on Mercedes-Benz SLK cars in 2025, grouped into the DVSA's test areas.
Suspension and lamps, reflectors and electrical equipment together account for 49.4% of recorded failure items. These are recorded failures across the model, not faults every car has.
The 10 most common SLK MOT failures
Specific items recorded on Mercedes-Benz SLK cars that failed their 2025 MOT, as a share of all recorded failure items.
Together these 10 items make up 39% of everything testers recorded against failed Mercedes-Benz SLK cars. The rest is spread across many smaller items, and one failed test often records several at once.
What to look at on a SLK
The recorded failures above, grouped by area, biggest first.
1
Suspension
Recorded most often: coil spring fractured or broken, ball joint excessively worn, pins and bushes pin or bush excessively worn and ball joint dust cover no longer prevents the ingress of dirt. 20% of failure items.
2
Tyres
Recorded most often: tread depth below requirements of 1.6mm, condition has ply or cords exposed and condition has a cut in excess of the requirements deep enough to reach the ply or cords. 10.2% of failure items.
3
Brakes
Recorded most often: rigid brake pipes excessively corroded. 3.6% of failure items.
4
Noise, emissions and leaks
Recorded most often: malfunction indicator lamp inoperative or indicates a malfunction. 2.6% of failure items.
The car's own MOT history matters more than any model average. A free MOT history check shows whether a specific SLK has failed on these items before, or had them noted as advisories. Buying one? See the used Mercedes-Benz SLK buying guide.
Already found one?
Check its finance, write-off, theft, mileage and keeper history with a £15 vehicle history report.
Mercedes-Benz SLK MOT FAQs
What is the Mercedes-Benz SLK MOT pass rate?
71.9% of Mercedes-Benz SLK cars passed their initial MOT first time in 2025, from 54,176 tests. That is 0.5 percentage points below the 72.3% average for all cars, and ranks 318th of 575 models.
What does a Mercedes-Benz SLK most commonly fail its MOT on?
The item testers recorded most often on Mercedes-Benz SLK cars failing their 2025 MOT was coil spring fractured or broken, on 9.2% of failure items. Next were ball joint excessively worn (5.5%) and tread depth below requirements of 1.6mm (4.3%).
Which area causes the most Mercedes-Benz SLK MOT failures?
Across every recorded failure item, the largest area was suspension at 28.8%, followed by lamps, reflectors and electrical equipment at 20.6%.
Do older Mercedes-Benz SLK cars fail their MOT more often?
Mercedes-Benz SLK cars aged 6 to 10 years passed 79.6% of MOT tests in 2025, against 70.4% for cars aged 11 years and over.
Does this mean every Mercedes-Benz SLK has these problems?
No. These are the items testers recorded across every Mercedes-Benz SLK that failed in 2025. They show where the model most often needs attention, not the condition of any individual car.
How do I see a specific Mercedes-Benz SLK's MOT history?
Enter its registration on the free Carpeep MOT history check to see that car's own test results, failures, advisories and recorded mileages.
MOT figures are aggregated from the DVSA MOT Anonymised data set for 2025: class 4 initial tests, retests excluded, with failure items from failed tests (advisories and minor defects excluded), licensed under the Open Government Licence v3.0. MOT results describe roadworthiness at test, not mechanical reliability.