1985 Mercedes-Benz 500 — MOT failures & pass rate
526 MOT tests on the 1985 Mercedes-Benz 500 are in this dataset, and 85.2% of them passed. All cars of a similar age fail 20.0% of the time, so this is 5.2pp better than the group it competes with. Failures cluster in lighting & signalling, brakes and body, structure & corrosion.
What the MOT record shows
No single area dominates — lighting & signalling (7.2%) and brakes (6.5%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, service brake performance and component mounting prescribed areas — headlamp aim alone was recorded 26 times.
Condition tracks the odometer closely. Failures run at 10.2% in the 30-60k band and 22.8% in the 150k+ band, a 12.6-point spread — more than double.
Brakes is the most common advisory, noted on 15.8% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 19.8% in 2021 to 13.0% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 7.2% | 38 |
| 2 | Brakes | 6.5% | 34 |
| 3 | Body, structure & corrosion | 4.2% | 22 |
| 4 | Suspension | 4.0% | 21 |
| 5 | Visibility | 3.8% | 20 |
| 6 | Emissions & environmental | 2.9% | 15 |
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 | 26 |
| 2 | Service brake performance | 24 |
| 3 | Component mounting prescribed areas | 21 |
| 4 | Wipers | 17 |
| 5 | Anti-lock braking system | 17 |
| 6 | Non catalyst emissions | 13 |
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 | 15.8% | 83 |
| 2 | Emissions & environmental | 14.4% | 76 |
| 3 | Suspension | 13.5% | 71 |
| 4 | Tyres | 11.2% | 59 |
| 5 | Body, structure & corrosion | 10.1% | 53 |
| 6 | Lighting & signalling | 4.8% | 25 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 30-60k | 49 | 10.2% |
| 60-90k | 123 | 11.4% |
| 90-120k | 142 | 15.5% |
| 120-150k | 111 | 13.5% |
| 150k+ | 79 | 22.8% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 121 | 19.8% |
| 2022 | 116 | 12.9% |
| 2023 | 119 | 16.8% |
| 2024 | 93 | 9.7% |
| 2025 | 77 | 13.0% |
What to check before buying a 1985 500
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 7.2% of tests. Start there.
- Lighting & signalling (7.2% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (6.5% 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.
- Body, structure & corrosion (4.2% of tests): The one to take seriously on older cars — corrosion to structural areas can be costly and is an MOT failure. Typical repair: £200–£1,500+.
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 1985 Mercedes-Benz 500s pass their MOT?
85.2% of the 526 1985 Mercedes-Benz 500 MOT tests in this dataset passed — a 14.8% fail rate.
What is the most common MOT failure on a 1985 Mercedes-Benz 500?
Lighting & signalling, recorded in 7.2% of tests, followed by brakes (6.5%).
Does the 1985 500 get worse with mileage?
Its MOT fail rate rises from 10.2% in the 30-60k band to 22.8% in the 150k+ band.
Methodology & source. Based on 526 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.