Mercedes-Benz GLC300d — MOT pass rate & failures
The Mercedes-Benz GLC300d passed 92.3% of its 30,245 MOT tests, covering model years 2019–2024. That is 1.7 percentage points better than the 9.4% fail rate across all Mercedes-Benz GLC versions, so the GLC300d is a stronger pick within the range. Failures concentrate in tyres, suspension and brakes.
What the MOT record shows
At component level the recurring items are tread depth, ball joint and brake pads — tread depth alone was recorded 505 times.
A 120-150k example is materially riskier than a 0-30k one: 14.6% versus 5.9%.
Advisories point at the next bill rather than this one: tyres was flagged on 21.7% of tests without failing them.
The trend is worsening — 5.4% of tests failed in 2022 against 8.4% in 2025, the usual pattern as a fleet ages.
How it compares
By model year
| Year | Tests | Pass rate | Fail rate |
|---|---|---|---|
| 2019 | 8,337 | 92.2% | 7.8% |
| 2020 | 13,547 | 92.0% | 8.0% |
| 2021 | 5,630 | 92.4% | 7.6% |
| 2022 | 2,684 | 93.2% | 6.8% |
| 2023 | 44 | 100.0% | 0.0% |
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 5.1% | 1,537 |
| 2 | Suspension | 1.1% | 338 |
| 3 | Brakes | 1.1% | 335 |
| 4 | Visibility | 1.1% | 322 |
| 5 | Lighting & signalling | 0.8% | 252 |
| 6 | Other defects | 0.4% | 105 |
| 7 | Emissions & environmental | 0.2% | 58 |
| 8 | Body, structure & corrosion | 0.2% | 57 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Tread depth | 505 |
| 2 | Ball joint | 345 |
| 3 | Brake pads | 342 |
| 4 | Headlamp aim | 263 |
| 5 | Wipers | 203 |
| 6 | Registration plates | 174 |
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 | 21.7% | 6,550 |
| 2 | Brakes | 9.1% | 2,741 |
| 3 | Other defects | 5.7% | 1,735 |
| 4 | Suspension | 3.6% | 1,083 |
| 5 | Visibility | 3.4% | 1,020 |
| 6 | Lighting & signalling | 0.4% | 112 |
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 | 11,883 | 5.9% |
| 30-60k | 15,367 | 8.6% |
| 60-90k | 2,620 | 10.3% |
| 90-120k | 310 | 12.3% |
| 120-150k | 48 | 14.6% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2022 | 2,156 | 5.4% |
| 2023 | 6,777 | 6.7% |
| 2024 | 9,496 | 8.2% |
| 2025 | 11,800 | 8.4% |
What to check before buying a Mercedes-Benz GLC300d
Focus on the areas it most often fails on — and remember MOT data covers testable defects only, not engine or gearbox health.
- Tyres (5.1% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Suspension (1.1% 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.
- Brakes (1.1% 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.
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 reliable is the Mercedes-Benz GLC300d at MOT time?
92.3% of the 30,245 Mercedes-Benz GLC300d MOT tests in this dataset passed — a 7.7% fail rate, better than the 9.4% average across all GLC versions.
What is the most common MOT failure on a Mercedes-Benz GLC300d?
Tyres, recorded in 5.1% of tests, followed by suspension (1.1%).
Does the GLC300d get worse with mileage?
Its MOT fail rate rises from 5.9% in the 0-30k band to 14.6% in the 120-150k band.
Methodology & source. Based on 30,245 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.