2018 Mercedes-Benz M8 — MOT failures & pass rate
The 2018 Mercedes-Benz M8 passed 78.5% of its 520 recorded MOT tests. That is 10.5 percentage points worse than all cars of a similar age, which fail at 11.0%. Failures cluster in suspension, brakes and emissions & environmental.
What the MOT record shows
No single area dominates — suspension (8.3%) and brakes (7.9%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are rbt (sp), coil spring and linkage pins and bushes — rbt (sp) alone was recorded 20 times.
A 150k+ example is materially riskier than a 60-90k one: 26.8% versus 11.5%.
Tyres is the most common advisory, noted on 14.6% of tests — work that passed today but is likely due soon.
The trend is worsening — 16.7% of tests failed in 2021 against 31.1% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Suspension | 8.3% | 43 |
| 2 | Brakes | 7.9% | 41 |
| 3 | Emissions & environmental | 3.6% | 19 |
| 4 | Lighting & signalling | 3.6% | 19 |
| 5 | Tyres | 2.5% | 13 |
| 6 | Seat belts & restraints | 2.5% | 13 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Rbt (sp) | 20 |
| 2 | Coil spring | 15 |
| 3 | Linkage pins and bushes | 15 |
| 4 | Malfunction indicator lamp | 12 |
| 5 | Service brake performance | 11 |
| 6 | Linkage ball joint dust cover | 11 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Tyres | 14.6% | 76 |
| 2 | Suspension | 11.5% | 60 |
| 3 | Brakes | 8.3% | 43 |
| 4 | Other defects | 4.0% | 21 |
| 5 | Emissions & environmental | 3.1% | 16 |
| 6 | Body, structure & corrosion | 1.9% | 10 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 60-90k | 52 | 11.5% |
| 90-120k | 85 | 15.3% |
| 120-150k | 92 | 17.4% |
| 150k+ | 284 | 26.8% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 108 | 16.7% |
| 2022 | 99 | 14.1% |
| 2023 | 107 | 24.3% |
| 2024 | 103 | 21.4% |
| 2025 | 103 | 31.1% |
What to check before buying a 2018 M8
The failure pattern for this year is specific enough to inspect against: suspension accounted for 8.3% of tests. Start there.
- Suspension (8.3% 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 (7.9% 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.
- Emissions & environmental (3.6% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
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 2018 Mercedes-Benz M8s pass their MOT?
78.5% of the 520 2018 Mercedes-Benz M8 MOT tests in this dataset passed — a 21.5% fail rate.
What is the most common MOT failure on a 2018 Mercedes-Benz M8?
Suspension, recorded in 8.3% of tests, followed by brakes (7.9%).
Does the 2018 M8 get worse with mileage?
Its MOT fail rate rises from 11.5% in the 60-90k band to 26.8% in the 150k+ band.
Methodology & source. Based on 520 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.