Mercedes-Benz 500 MOT pass rate & common failures
Across 42 model years and 5,824 tests, the Mercedes-Benz 500 passes its MOT 85.6% of the time. All cars of a similar age fail 21.4% of the time, so this is 7.0pp better than the group it competes with. Its most common failure areas are lighting & signalling, brakes and suspension.
What the MOT record shows
Lighting & signalling dominates the failure mix at 8.5% of all tests — 3.6 points clear of brakes, so it is the first thing to check.
At component level the recurring items are headlamp aim, service brake performance and ball joint dust cover — headlamp aim alone was recorded 247 times.
Mileage is the strongest signal on the record: 7.0% of 0-30k cars fail, rising to 18.5% once past 150k — 2.6× the risk.
Advisories point at the next bill rather than this one: suspension was flagged on 18.8% of tests without failing them.
The trend is improving — the fail rate fell from 16.5% in 2021 to 13.1% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every 500 model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 1981 | 53 | 86.8% | 13.2% | Lighting & signalling |
| 1982 | 107 | 80.4% | 19.6% | Lighting & signalling |
| 1983 | 208 | 83.7% | 16.4% | Lighting & signalling |
| 1984 | 236 | 87.3% | 12.7% | Lighting & signalling |
| 1985 | 526 | 85.2% | 14.8% | Lighting & signalling |
| 1986 | 416 | 81.7% | 18.3% | Lighting & signalling |
| 1987 | 507 | 82.5% | 17.5% | Lighting & signalling |
| 1988 | 551 | 86.0% | 14.0% | Lighting & signalling |
| 1989 | 624 | 87.5% | 12.5% | Lighting & signalling |
| 1990 | 609 | 85.5% | 14.4% | Lighting & signalling |
| 1991 | 720 | 86.8% | 13.2% | Lighting & signalling |
| 1992 | 499 | 87.8% | 12.2% | Lighting & signalling |
| 1993 | 420 | 88.1% | 11.9% | Lighting & signalling |
| 1994 | 35 | 80.0% | 20.0% | Lighting & signalling |
| 2003 | 39 | 76.9% | 23.1% | Brakes |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 8.5% | 493 |
| 2 | Brakes | 4.8% | 281 |
| 3 | Suspension | 4.1% | 239 |
| 4 | Emissions & environmental | 3.5% | 202 |
| 5 | Body, structure & corrosion | 3.1% | 178 |
| 6 | Visibility | 3.1% | 178 |
| 7 | Tyres | 1.6% | 92 |
| 8 | Steering | 1.2% | 72 |
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 | 247 |
| 2 | Service brake performance | 167 |
| 3 | Ball joint dust cover | 151 |
| 4 | Position lamp | 136 |
| 5 | Wipers | 115 |
| 6 | Washers | 111 |
| 7 | Non catalyst emissions | 111 |
| 8 | Catalyst emissions | 85 |
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 | 18.8% | 1,092 |
| 2 | Brakes | 16.7% | 974 |
| 3 | Emissions & environmental | 12.8% | 745 |
| 4 | Tyres | 11.2% | 650 |
| 5 | Steering | 8.2% | 479 |
| 6 | Body, structure & corrosion | 7.6% | 443 |
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 | 312 | 7.0% |
| 30-60k | 609 | 9.4% |
| 60-90k | 1,431 | 12.2% |
| 90-120k | 1,609 | 16.7% |
| 120-150k | 1,107 | 16.2% |
| 150k+ | 753 | 18.5% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 1,361 | 16.5% |
| 2022 | 1,254 | 13.7% |
| 2023 | 1,196 | 15.1% |
| 2024 | 1,020 | 12.9% |
| 2025 | 993 | 13.1% |
What to check before buying a Mercedes-Benz 500
- Lighting & signalling (8.5% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (4.8% 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.
- Suspension (4.1% 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.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the Mercedes-Benz 500?
85.6% of the 5,824 Mercedes-Benz 500 MOT tests in this dataset passed, a 14.4% fail rate, across model years 1980–2021.
What does the Mercedes-Benz 500 most often fail its MOT on?
Lighting & signalling, recorded in 8.5% of tests, then brakes (4.8%).
How much does mileage affect 500 MOT results?
Fail rates run at 7.0% for cars in the 0-30k band and 18.5% for 150k+, a 11.4-point difference.
Methodology & source. Based on 5,824 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.