2004 Mercedes-Benz SLK MOT pass rate, common failures & what to check
In 2025, 66.2% of Mercedes-Benz SLKs first used in 2004 passed their MOT first time, against 57.8% for all cars first used in 2004. Across 9,029 SLK first tests from 2023 to 2025, the most common failure areas were suspension, lamps and electrical equipment and brakes.
This page analyses first MOT tests for Mercedes-Benz SLKs first used in 2004 (all trims grouped): 2021 to 2025 for the pass-rate trend, and 2023 to 2025 for the failure and advisory analysis — plus what is worth checking before you buy one.
Data: DVSA anonymised MOT tests to December 2025 · Calculated by SortedCars · Updated October 2026
How the 2004 Mercedes-Benz SLK MOT pass rate has changed
Share of first tests passed in each year, SLKs first used in 2004 against all cars first used in 2004 (any make or fuel; not adjusted for mileage, fuel or use). In 2025 the SLK figure was 8.4 points higher.
View this chart as a table
| Test year | 2004 SLK | All cars first used 2004 | SLK first tests |
|---|---|---|---|
| 2021 | 64.5% | 53.9% | 3,491 |
| 2022 | 64.5% | 55.2% | 3,379 |
| 2023 | 65.4% | 56.0% | 3,231 |
| 2024 | 65.0% | 56.4% | 3,037 |
| 2025 | 66.2% | 57.8% | 2,761 |
Common 2004 Mercedes-Benz SLK MOT failures
Share of the 3,114 failed first tests (2023–2025) with at least one failure in each area. A test can fail in more than one area, so the shares add up to more than 100%.
Most common failure items
| DVSA failure item | Share of failed first tests | Tests |
|---|---|---|
| Coil spring: fractured or broken | 18.7% | 583 |
| Ball joint: excessively worn | 10.4% | 325 |
| Malfunction indicator lamp: inoperative or indicates a malfunction | 10.1% | 313 |
| Steering rack: gaiter missing or no longer prevents the ingress of dirt | 9.0% | 279 |
| Suspension arm pins and bushes: pin or bush excessively worn | 6.5% | 203 |
Item names are DVSA’s own wording. 2023–2025 combined.
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Typical repair costs for common MOT failures
Typical UK garage prices for the job, not for an SLK in particular, and not a quote.
| Failure item | Typical job | Typical UK price | Usual range |
|---|---|---|---|
| Coil spring: fractured or broken | Coil spring replacement | £248 | £175–£400 |
| Ball joint: excessively worn | Ball joint replacement | £90 | £60–£150 |
| Suspension arm pins and bushes: pin or bush excessively worn | Suspension arm replacement | £150 | £120–£180 |
From published UK repair-cost guides, checked September 2026. Only jobs with a published typical price are shown.
What to check on a 2004 Mercedes-Benz SLK before buying
The three areas where failed first tests most often had a fault, 2023–2025.
- Suspension. Worth looking behind the front wheels with a torch at the coil springs, and listening for knocks over bumps on the test drive.
- Lamps and electrics. Ask someone to watch while you work the brake lights, indicators, sidelights, dipped and main beam, and the number-plate lamps.
- Brakes. Worth looking at the discs and pads through the wheel spokes for scoring and a worn lip, and noticing on the test drive whether the car pulls to one side or the pedal feels long.
Common 2004 Mercedes-Benz SLK MOT advisories
Advisories are points the tester noted that did not fail the car. Most common on 2004 SLKs, as a share of all 9,029 first tests, 2023–2025.
| DVSA advisory item | Share of first tests | Tests |
|---|---|---|
| Rigid brake pipes: corroded, covered in grease or other material | 15.5% | 1,396 |
| Tread depth: worn close to legal limit/worn on edge | 12.9% | 1,163 |
| Tyre condition: slightly damaged/cracking or perishing | 8.9% | 803 |
| Brake discs: worn, pitted or scored, but not seriously weakened | 7.1% | 637 |
| Engine oil leaks: leak, but not excessive | 6.3% | 571 |
Questions about the 2004 Mercedes-Benz SLK MOT
What is the MOT pass rate of a 2004 Mercedes-Benz SLK?
In 2025, 66.2% of SLKs first used in 2004 passed their MOT first time, against 57.8% for all cars first used in 2004. A car fixed during the test counts as a fail.
What does a 2004 SLK most often fail its MOT on?
Suspension (in 44.3% of failed first tests, 2023–2025), lamps and electrical equipment (34.7%) and brakes (25.4%). The single most common item was “Coil spring: fractured or broken” (18.7%).
How often does a 2004 Mercedes-Benz SLK fail its MOT?
In 2025, 33.8% of first tests on SLKs first used in 2004 did not pass first time: 28.9% failed, and a further 4.9% had a fault fixed during the test (counted as a fail here). Across 2023–2025, 3,114 of 9,029 first tests did not pass first time.
What are the most common 2004 Mercedes-Benz SLK MOT advisories?
“Rigid brake pipes: corroded, covered in grease or other material” (on 15.5% of first tests, 2023–2025), “Tread depth: worn close to legal limit/worn on edge” (12.9%), “Tyre condition: slightly damaged/cracking or perishing” (8.9%), “Brake discs: worn, pitted or scored, but not seriously weakened” (7.1%) and “Engine oil leaks: leak, but not excessive” (6.3%).
Is a 2004 Mercedes-Benz SLK reliable?
An MOT pass rate shows what failed at the test, not how reliable a car is. For this group of cars the first-time pass rate went from 64.5% in 2021 to 66.2% in 2025. For one particular car, its own MOT history matters more than the average.
Other cars first used in 2004
The most-tested cars from the same year. Each page uses the same method.
2004 Ford Fiesta MOT statistics · 2004 MINI Hatch MOT statistics · 2004 Ford Focus MOT statistics · 2004 Toyota Yaris MOT statistics · 2004 Volkswagen Polo MOT statistics
Checking a specific 2004 SLK?
The numbers above cover every SLK first used in 2004 and tested in Great Britain. Our free check shows the actual MOT history, mileage record and tax status of the one you are looking at.
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