1999 Mercedes-Benz C-Class — MOT failures & pass rate
6,367 MOT tests on the 1999 Mercedes-Benz C-Class are in this dataset, and 79.1% of them passed. Against executive cars of a similar age (23.3% fail rate), the 1999 C-Class comes out 2.4pp better. Failures cluster in lighting & signalling, suspension and brakes.
What the MOT record shows
One area stands out: lighting & signalling, recorded in 13.3% of tests against 8.8% for the next-worst category.
At component level the recurring items are component mounting prescribed areas, individual direction indicators and side repeaters — component mounting prescribed areas alone was recorded 288 times.
Condition tracks the odometer closely. Failures run at 8.3% in the 0-30k band and 27.8% in the 150k+ band, a 19.5-point spread — more than double.
Fuel type barely separates them — petrol fails 20.7% of the time against 21.9% for diesel.
Suspension is the most common advisory, noted on 33.4% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 13.3% | 849 |
| 2 | Suspension | 8.8% | 562 |
| 3 | Brakes | 6.6% | 423 |
| 4 | Body, structure & corrosion | 4.8% | 304 |
| 5 | Visibility | 4.1% | 260 |
| 6 | Tyres | 3.6% | 231 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Component mounting prescribed areas | 288 |
| 2 | Individual direction indicators | 260 |
| 3 | Side repeaters | 232 |
| 4 | Headlamp aim | 230 |
| 5 | Position lamp | 212 |
| 6 | Catalyst emissions | 203 |
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 | 33.4% | 2,124 |
| 2 | Brakes | 33.3% | 2,122 |
| 3 | Tyres | 22.3% | 1,417 |
| 4 | Emissions & environmental | 13.4% | 854 |
| 5 | Lighting & signalling | 13.3% | 844 |
| 6 | Other defects | 13.1% | 832 |
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 | 72 | 8.3% |
| 30-60k | 521 | 10.6% |
| 60-90k | 1,421 | 15.7% |
| 90-120k | 1,826 | 21.5% |
| 120-150k | 1,333 | 23.8% |
| 150k+ | 1,178 | 27.8% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 5,401 | 20.7% |
| Diesel | 966 | 21.9% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,903 | 22.0% |
| 2022 | 1,530 | 20.8% |
| 2023 | 1,201 | 19.7% |
| 2024 | 944 | 19.5% |
| 2025 | 789 | 21.6% |
What to check before buying a 1999 C-Class
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 13.3% of tests. Start there.
- Lighting & signalling (13.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (8.8% 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.
- Brakes (6.6% 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 1999 Mercedes-Benz C-Classs pass their MOT?
79.1% of the 6,367 1999 Mercedes-Benz C-Class MOT tests in this dataset passed — a 20.9% fail rate.
What is the most common MOT failure on a 1999 Mercedes-Benz C-Class?
Lighting & signalling, recorded in 13.3% of tests, followed by suspension (8.8%).
Does the 1999 C-Class get worse with mileage?
Its MOT fail rate rises from 8.3% in the 0-30k band to 27.8% in the 150k+ band.
Methodology & source. Based on 6,367 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.