2025 MOT results
Mercedes-Benz SLK-Class common problems
The most common reason a Mercedes-Benz SLK-Class fails its MOT is a broken coil spring, on 17.7% of its 15,249 failed tests in 2025. Against other cars of the same age, 4 faults stand out, the widest gaps being: a broken coil spring at 17.7% of failures against 8.7% expected; the airbag light on at 4.5% of failures against 2.3% expected; a worn steering or suspension joint at 10.2% of failures against 5.7% expected.
- Tests in 2025 54,180 Cars aged three and over
- Failed first time 28.1% 15,249 tests
- Found a dangerous defect 6.9% Unsafe to drive away
- Ended with an advisory 52.6% A problem to watch, not a failure
What fails a Mercedes-Benz SLK-Class MOT
Each bar is the share of failed Mercedes-Benz SLK-Class tests with that defect. Where we can compare it with cars of the same registration years, the marker shows what an average car of those ages records (12 of the 12 items below).
Most common reasons for failure
A test can fail for more than one defect, so shares add up to more than 100%.
| Defect | Share of failed tests |
|---|---|
| Coil spring: fractured or broken Suspension | 17.7% |
| Suspension arms: ball joint excessively worn Suspension | 10.2% |
| Tyres: tread depth below requirements of 1.6mm Tyres | 7.0% |
| Tyres: ply or cords exposed Tyres | 6.0% |
| Malfunction indicator lamp: inoperative or indicates a malfunction Noise, emissions and leaks | 5.9% |
| Rigid brake pipes: excessively corroded Brakes | 5.1% |
| Tyres: cut in excess of the requirements deep enough to reach the ply or cords Tyres | 4.7% |
| Wipers: does not clear the windscreen effectively Visibility | 4.6% |
| SRS malfunction indicator lamp: warning lamp indicates a fault Seat belts and supplementary restraint systems | 4.5% |
| Position lamp: not working Lamps, reflectors and electrical equipment | 4.5% |
| Stop lamp: not working Lamps, reflectors and electrical equipment | 4.5% |
| Suspension arms: pin or bush excessively worn Suspension | 4.1% |
Source:DVSA,UK Motoring analysis 2025 Updated
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Broken coil spring
17.7% of failures 8.7% expected 2 times as often
A broken suspension spring, which usually snaps in the bottom coil and often fails on both sides within a year.
Look at each corner for a sagging ride height, and listen for a knock over speed bumps.
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Worn steering or suspension joint
10.2% of failures 5.7% expected 1.8 times as often
Play in a steering or suspension joint, where a worn ball and socket lets the wheel move where it should not.
A knock at low speed over rough ground, or vague steering, is the usual warning.
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Tyre worn below the legal limit
7.0% of failures 6.7% expected about as expected
A tyre worn past the 1.6mm legal minimum across the middle three quarters of the tread.
A 20p coin in the main grooves: if the outer band of the coin is visible, the tyre is close to the limit.
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Tyre worn through to the cords
6.0% of failures 4.1% expected 1.5 times as often
The tyre is worn or damaged far enough to expose the cords underneath, which is a dangerous defect.
Run a hand round the inner and outer walls of each tyre, which is where kerbing shows.
-
Engine management light on
5.9% of failures 5.6% expected about as expected
The engine management light is on, or has been disconnected. Either fails the test.
A cheap code reader on the diagnostic socket will say what the car has stored before you pay for a test.
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Corroded brake pipes
5.1% of failures 2.9% expected 1.8 times as often
Corroded or damaged brake pipework. It is a safety item, and on older cars the rear pipes go first.
Look along the pipes under the sills with a torch; flaking rust rather than surface staining is the problem.
Which parts of the car fail
Suspension is the area that most often fails a Mercedes-Benz SLK-Class, on 44.0% of failed tests. That is also where it differs most from cars of the same registration years, which record 38.0%.
Failure categories
DVSA's own sections of the test. The marker is what cars of the same registration years record.
| Defect category | Share of failed tests |
|---|---|
| Suspension | 44.0% |
| Lamps, reflectors and electrical equipment | 29.1% |
| Tyres | 22.1% |
| Brakes | 21.8% |
| Visibility | 11.9% |
| Noise, emissions and leaks | 9.3% |
| Seat belts and supplementary restraint systems | 5.0% |
| Body, chassis, structure | 4.9% |
Source:DVSA,UK Motoring analysis 2025 Updated
What testers warn about
52.6% of Mercedes-Benz SLK-Class tests ended with at least one advisory: a fault the tester found that did not fail the test. On Mercedes-Benz SLK-Classes, these are the items to ask about on a car you are viewing, because they are what the last tester expected to go next.
Most common advisories
Share of all tests, passes included.
| Advisory | Share of tests |
|---|---|
| Tread depth: worn close to legal limit or worn on edge Tyres | 15.9% |
| Rigid brake pipes: corroded, covered in grease or other material Brakes | 11.4% |
| Tyres: slightly damaged or cracking or perishing Tyres | 8.6% |
| Brake discs: worn, pitted or scored, but not seriously weakened Brakes | 8.4% |
| Brake pads: wearing thin Brakes | 5.1% |
| Wheel bearings: slight play Suspension | 4.8% |
| Suspension arms: pin or bush worn but not resulting in excessive movement Suspension | 4.7% |
| Engine oil leak, but not excessive Noise, emissions and leaks | 4.1% |
| Sub-frame: corroded but not seriously weakened Suspension | 3.4% |
| Coil spring: corroded Suspension | 3.3% |
| Suspension arms: ball joint has slight play Suspension | 2.7% |
| Brake discs: worn, but not excessively Brakes | 2.6% |
Source:DVSA,UK Motoring analysis 2025 Updated
What changes as a Mercedes-Benz SLK-Class gets older
A 2015 Mercedes-Benz SLK-Class failed 20.0% of its MOT tests in 2025; a 2004 one failed 33.8%. What fails changes as much as how often, and these are the two years themselves rather than an average across them.
2015 Mercedes-Benz SLK-Class 20.0% failed, from 4,848 tests
- Broken coil spring 21.6%
- Tyre worn through to the cords 12.6%
- Tyre worn below the legal limit 11.1%
- Cut tyre 8.9%
- Engine management light on 6.7%
- Lighting fault 6.6%
2004 Mercedes-Benz SLK-Class 33.8% failed, from 2,761 tests
- Broken coil spring 17.5%
- Worn steering or suspension joint 10.7%
- Steering fault 10.2%
- Engine management light on 8.4%
- Worn suspension bushes 6.8%
- Headlamp aim out of line 6.3%
Shares are of each year's failed tests. Every MOT a particular car has had, with the defects and advisories written at each test, is on GOV.UK's MOT history service from the registration, free.
Mercedes-Benz SLK-Class problems: common questions
What is the most common problem with a Mercedes-Benz SLK-Class?
Of the faults that fail an MOT, “Coil spring: fractured or broken” is the most common: it appears on 17.7% of failed Mercedes-Benz SLK-Class tests. Across categories, suspension is the area that most often fails one, on 44.0% of failed tests.
How often does a Mercedes-Benz SLK-Class fail its MOT?
28.1% of Mercedes-Benz SLK-Class tests in 2025 were not passed first time, from 54,180 tests of cars aged three and over. Allowing for the age and mileage of the cars tested, that gives it a UK Motoring Reliability Score of 58 out of 100, where 50 is as expected.
Does anything fail more often on a Mercedes-Benz SLK-Class than on other cars?
Yes. “Coil spring: fractured or broken” appears on 17.7% of its failures against 8.7% for cars of the same age, and “SRS malfunction indicator lamp: warning lamp indicates a fault” appears on 4.5% of its failures against 2.3% for cars of the same age. Where an item is missing from the national figures for a year, we use the smallest share those figures show, so the comparison never overstates the difference.
Are these the same as breakdowns or known faults?
No. These are the items a tester recorded at the MOT, which covers condition and safety: lamps, brakes, tyres, suspension, corrosion and emissions. A gearbox that is unpleasant, an infotainment screen that has died, or a car that will not start on a cold morning are not part of the test, so they are not in these figures.
Where do the figures come from?
Every normal MOT test of a Mercedes-Benz SLK-Class aged three and over in Great Britain in 2025, from DVSA's anonymised MOT results. Retests are excluded, and the same fault on more than one wheel counts once.
Data stories to read next
Data sources and methodology
| Figures | Source | Period | Records | Updated |
|---|---|---|---|---|
| MOT defects and advisories | Anonymised MOT tests and results Driver and Vehicle Standards Agency Derived statistics UK Motoring | 2025 | 54,180 MOT tests | 19 September 2026 |
- Shares for defects are of failed tests; shares for advisories are of all tests. A test can carry several defects, so shares add to more than 100%.
- The expected share is what an average car of the same registration years records, weighted by where this model’s failures fall. Where an item is outside the national figures for a year, the smallest share those figures show is used in its place, which is an upper bound, so the comparison never overstates a model’s problems. No expectation is published where less than 80% of the model’s failures can be compared.
- Great Britain only: DVSA does not run MOT testing in Northern Ireland. Cars under three years old are not tested.
- The descriptions of what each part does are general and the same on every model. Every figure comes from the MOT data.
Contains public sector information licensed under the Open Government Licence v3.0.