2005 Mercedes-Benz C-Class — MOT failures & pass rate
Across 71,633 MOT tests, the 2005 Mercedes-Benz C-Class recorded a 72.6% pass rate. Executive cars of a similar age fail 24.1% of the time, so this is 3.3pp worse than the group it competes with. Failures cluster in suspension, lighting & signalling and brakes.
What the MOT record shows
Suspension dominates the failure mix at 17.6% of all tests — 4.5 points clear of lighting & signalling, so it is the first thing to check.
At component level the recurring items are ball joint, headlamp aim and coil spring — ball joint alone was recorded 6,966 times.
Mileage is the strongest signal on the record: 15.5% of 0-30k cars fail, rising to 29.6% once past 150k.
Fuel type barely separates them — petrol fails 26.8% of the time against 28.1% for diesel.
Advisories point at the next bill rather than this one: suspension was flagged on 43.0% of tests without failing them.
The trend is improving — the fail rate fell from 28.5% in 2021 to 26.2% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 17.6% | 12,611 |
| 2 | Lighting & signalling | 13.1% | 9,415 |
| 3 | Brakes | 8.6% | 6,140 |
| 4 | Tyres | 6.2% | 4,430 |
| 5 | Emissions & environmental | 6.0% | 4,303 |
| 6 | Visibility | 4.2% | 2,987 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Ball joint | 6,966 |
| 2 | Headlamp aim | 5,479 |
| 3 | Coil spring | 4,795 |
| 4 | Tread depth | 3,255 |
| 5 | Headlamp | 2,579 |
| 6 | Pins and bushes | 2,535 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Suspension | 43.0% | 30,817 |
| 2 | Brakes | 37.0% | 26,517 |
| 3 | Tyres | 27.4% | 19,615 |
| 4 | Lighting & signalling | 14.3% | 10,255 |
| 5 | Other defects | 12.2% | 8,723 |
| 6 | Body, structure & corrosion | 9.4% | 6,710 |
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 | 595 | 15.5% |
| 30-60k | 4,557 | 19.3% |
| 60-90k | 13,348 | 24.8% |
| 90-120k | 19,849 | 27.8% |
| 120-150k | 16,808 | 29.4% |
| 150k+ | 16,321 | 29.6% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 39,100 | 26.8% |
| Diesel | 32,532 | 28.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 19,537 | 28.5% |
| 2022 | 16,955 | 27.4% |
| 2023 | 14,255 | 27.2% |
| 2024 | 11,624 | 26.8% |
| 2025 | 9,262 | 26.2% |
What to check before buying a 2005 C-Class
On a 2005 C-Class, suspension is what the MOT record says goes wrong most — it appeared in 17.6% of tests. Check these areas before you commit.
- Suspension (17.6% 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 (13.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (8.6% 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 2005 Mercedes-Benz C-Classs pass their MOT?
72.6% of the 71,633 2005 Mercedes-Benz C-Class MOT tests in this dataset passed — a 27.4% fail rate.
What is the most common MOT failure on a 2005 Mercedes-Benz C-Class?
Suspension, recorded in 17.6% of tests, followed by lighting & signalling (13.1%).
Does the 2005 C-Class get worse with mileage?
Its MOT fail rate rises from 15.5% in the 0-30k band to 29.6% in the 150k+ band.
Methodology & source. Based on 71,633 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.