2004 Mercedes-Benz Clk — MOT failures & pass rate
The 2004 Mercedes-Benz Clk passed 73.4% of its 28,784 recorded MOT tests. Against coupes & convertibles of a similar age (22.4% fail rate), the 2004 Clk comes out 4.2pp worse. Failures cluster in suspension, lighting & signalling and brakes.
What the MOT record shows
One area stands out: suspension, recorded in 16.1% of tests against 12.6% for the next-worst category.
At component level the recurring items are headlamp aim, ball joint and coil spring — headlamp aim alone was recorded 2,379 times.
Mileage is the strongest signal on the record: 15.6% of 0-30k cars fail, rising to 29.5% once past 150k.
The petrol cars hold up better: 26.1% fail against 30.3% for diesel, a 4.2-point gap across 28,784 tests.
Brakes is the most common advisory, noted on 36.0% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 28.1% in 2021 to 25.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 16.1% | 4,620 |
| 2 | Lighting & signalling | 12.6% | 3,615 |
| 3 | Brakes | 8.3% | 2,388 |
| 4 | Tyres | 5.9% | 1,714 |
| 5 | Visibility | 4.0% | 1,157 |
| 6 | Emissions & environmental | 3.6% | 1,038 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 2,379 |
| 2 | Ball joint | 2,182 |
| 3 | Coil spring | 2,175 |
| 4 | Headlamp | 1,756 |
| 5 | Pins and bushes | 1,077 |
| 6 | Tread depth | 962 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Brakes | 36.0% | 10,373 |
| 2 | Suspension | 34.1% | 9,810 |
| 3 | Tyres | 27.3% | 7,863 |
| 4 | Lighting & signalling | 17.8% | 5,136 |
| 5 | Emissions & environmental | 11.6% | 3,350 |
| 6 | Body, structure & corrosion | 9.2% | 2,641 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 443 | 15.6% |
| 30-60k | 2,585 | 18.4% |
| 60-90k | 7,205 | 24.9% |
| 90-120k | 9,308 | 27.8% |
| 120-150k | 5,762 | 29.5% |
| 150k+ | 3,390 | 29.5% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 25,468 | 26.1% |
| Diesel | 3,316 | 30.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 7,274 | 28.1% |
| 2022 | 6,395 | 26.1% |
| 2023 | 5,816 | 27.0% |
| 2024 | 4,996 | 25.8% |
| 2025 | 4,303 | 25.1% |
What to check before buying a 2004 Clk
The failure pattern for this year is specific enough to inspect against: suspension accounted for 16.1% of tests. Start there.
- Suspension (16.1% of tests): Worn drop links, bushes, springs or shocks — listen for knocks over bumps and check for uneven tyre wear. Typical repair: £150–£450 per corner.
- Lighting & signalling (12.6% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (8.3% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 2004 Mercedes-Benz Clks pass their MOT?
73.4% of the 28,784 2004 Mercedes-Benz Clk MOT tests in this dataset passed — a 26.6% fail rate.
What is the most common MOT failure on a 2004 Mercedes-Benz Clk?
Suspension, recorded in 16.1% of tests, followed by lighting & signalling (12.6%).
Does the 2004 Clk get worse with mileage?
Its MOT fail rate rises from 15.6% in the 0-30k band to 29.5% in the 150k+ band.
Methodology & source. Based on 28,784 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.