Mercedes-Benz 350 MOT pass rate & common failures
1,056 MOT tests on the Mercedes-Benz 350 (1980–2023) give it an 83.2% pass rate. All cars of a similar age fail 20.8% of the time, so this is 4.0pp better than the group it competes with. Its most common failure areas are suspension, brakes and lighting & signalling.
What the MOT record shows
No single area dominates — suspension (5.8%) and brakes (5.5%) 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 tread depth — headlamp aim alone was recorded 40 times.
Mileage is the strongest signal on the record: 9.5% of 0-30k cars fail, rising to 24.4% once past 150k — 2.6× the risk.
Brakes is the most common advisory, noted on 18.4% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 21.8% in 2021 to 14.9% in 2025, as the worst-kept examples leave the fleet.
How it compares
By model year
Every 350 model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 1980 | 119 | 79.0% | 21.0% | Suspension |
| 2004 | 46 | 73.9% | 26.1% | Lighting & signalling |
| 2007 | 30 | 80.0% | 20.0% | Lighting & signalling |
| 2009 | 72 | 86.1% | 13.9% | Lighting & signalling |
| 2010 | 146 | 80.8% | 19.2% | Brakes |
| 2011 | 106 | 80.2% | 19.8% | Tyres |
| 2012 | 95 | 77.9% | 22.1% | Suspension |
| 2013 | 50 | 82.0% | 18.0% | Tyres |
| 2014 | 66 | 84.9% | 15.2% | Tyres |
| 2015 | 45 | 86.7% | 13.3% | Other defects |
| 2016 | 82 | 87.8% | 12.2% | Tyres |
| 2017 | 35 | 94.3% | 5.7% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 5.8% | 61 |
| 2 | Brakes | 5.5% | 58 |
| 3 | Lighting & signalling | 4.8% | 51 |
| 4 | Tyres | 4.5% | 47 |
| 5 | Emissions & environmental | 2.3% | 24 |
| 6 | Visibility | 1.3% | 14 |
| 7 | Body, structure & corrosion | 1.0% | 11 |
| 8 | Road wheels | 0.9% | 9 |
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 | 40 |
| 2 | Service brake performance | 23 |
| 3 | Tread depth | 23 |
| 4 | Ball joint | 22 |
| 5 | Rigid brake pipes | 21 |
| 6 | Coil spring | 18 |
| 7 | Headlamp | 18 |
| 8 | Rbt (sp) | 17 |
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 | 18.4% | 194 |
| 2 | Tyres | 17.1% | 181 |
| 3 | Suspension | 14.9% | 157 |
| 4 | Emissions & environmental | 6.2% | 65 |
| 5 | Other defects | 5.1% | 54 |
| 6 | Visibility | 4.1% | 43 |
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 | 74 | 9.5% |
| 30-60k | 260 | 13.5% |
| 60-90k | 305 | 18.0% |
| 90-120k | 241 | 19.5% |
| 120-150k | 98 | 14.3% |
| 150k+ | 78 | 24.4% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 568 | 16.2% |
| Petrol | 452 | 17.7% |
| Hybrid | 36 | 13.9% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 211 | 21.8% |
| 2022 | 204 | 14.7% |
| 2023 | 219 | 16.0% |
| 2024 | 208 | 16.4% |
| 2025 | 214 | 14.9% |
What to check before buying a Mercedes-Benz 350
- Suspension (5.8% 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 (5.5% 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.
- Lighting & signalling (4.8% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£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
What is the MOT pass rate for the Mercedes-Benz 350?
83.2% of the 1,056 Mercedes-Benz 350 MOT tests in this dataset passed, a 16.8% fail rate, across model years 1980–2023.
What does the Mercedes-Benz 350 most often fail its MOT on?
Suspension, recorded in 5.8% of tests, then brakes (5.5%).
How much does mileage affect 350 MOT results?
Fail rates run at 9.5% for cars in the 0-30k band and 24.4% for 150k+, a 14.9-point difference.
Methodology & source. Based on 1,056 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.