1999 Mercedes-Benz S-Class — MOT failures & pass rate
Across 1,373 MOT tests analysed for the 1999 Mercedes-Benz S-Class, the most common recorded failure areas were lighting & signalling, suspension and visibility. Its pass rate of 78.8% was above the average for cars of a similar age (75.5%). Higher-mileage examples failed more often — 27.1% in the 150k+ group versus 8.3% in the 0-30k group.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 12.7% | 174 |
| 2 | Suspension | 9.5% | 130 |
| 3 | Visibility | 8.0% | 110 |
| 4 | Brakes | 6.5% | 89 |
| 5 | Body, structure & corrosion | 4.2% | 57 |
| 6 | Seat belts & restraints | 3.9% | 53 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Wipers | 93 |
| 2 | Headlamp aim | 70 |
| 3 | Individual direction indicators | 58 |
| 4 | Component mounting prescribed areas | 55 |
| 5 | Headlamp | 49 |
| 6 | Catalyst emissions | 49 |
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 | 31.3% | 429 |
| 2 | Suspension | 25.7% | 353 |
| 3 | Tyres | 22.7% | 312 |
| 4 | Lighting & signalling | 14.6% | 201 |
| 5 | Emissions & environmental | 14.6% | 200 |
| 6 | Other defects | 9.5% | 130 |
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 | 48 | 8.3% |
| 30-60k | 144 | 12.5% |
| 60-90k | 343 | 16.3% |
| 90-120k | 394 | 25.9% |
| 120-150k | 233 | 22.3% |
| 150k+ | 199 | 27.1% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 401 | 22.2% |
| 2022 | 339 | 21.8% |
| 2023 | 253 | 19.4% |
| 2024 | 198 | 21.2% |
| 2025 | 182 | 20.3% |
What to check before buying a 1999 S-Class
Before buying a 1999 Mercedes-Benz S-Class, focus on the areas it most often fails on. Lighting & signalling accounted for 12.7% of tests for this year.
- Lighting & signalling (12.7% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Suspension (9.5% 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.
- Visibility (8.0% of tests): Wipers, washers, mirrors and screen damage — usually inexpensive, but check for chips in the driver's line of sight. Typical repair: £15–£150.
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 S-Classs pass their MOT?
78.8% of the 1,373 1999 Mercedes-Benz S-Class MOT tests in this dataset passed — a 21.2% fail rate.
What is the most common MOT failure on a 1999 Mercedes-Benz S-Class?
Lighting & signalling, recorded in 12.7% of tests, followed by suspension (9.5%).
Does the 1999 S-Class get worse with mileage?
Its MOT fail rate rises from 8.3% in the 0-30k band to 27.1% in the 150k+ band.
Methodology & source. Based on 1,373 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-01. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.