2021 Mercedes-Benz GLC — MOT failures & pass rate
14,581 MOT tests on the 2021 Mercedes-Benz GLC are in this dataset, and 92.9% of them passed. That is 1.0 percentage points better than mid-size SUVs of a similar age, which fail at 8.1%. Failures cluster in tyres, visibility and brakes.
What the MOT record shows
Tyres dominates the failure mix at 5.2% of all tests — 4.1 points clear of visibility, so it is the first thing to check.
At component level the recurring items are tread depth, brake pads and headlamp aim — tread depth alone was recorded 283 times.
Condition tracks the odometer closely. Failures run at 5.8% in the 0-30k band and 12.4% in the 90-120k band, a 6.6-point spread — more than double.
Fuel type barely separates them — hybrid fails 6.6% of the time against 7.2% for diesel.
Advisories point at the next bill rather than this one: tyres was flagged on 21.6% of tests without failing them.
The trend is worsening — 4.3% of tests failed in 2023 against 7.1% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 5.2% | 755 |
| 2 | Visibility | 1.1% | 160 |
| 3 | Brakes | 1.1% | 156 |
| 4 | Lighting & signalling | 0.9% | 133 |
| 5 | Suspension | 0.4% | 53 |
| 6 | Other defects | 0.3% | 37 |
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 | 283 |
| 2 | Brake pads | 184 |
| 3 | Headlamp aim | 150 |
| 4 | Wipers | 87 |
| 5 | Washers | 77 |
| 6 | Registration plates | 59 |
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 | 21.6% | 3,151 |
| 2 | Brakes | 7.4% | 1,084 |
| 3 | Other defects | 5.4% | 786 |
| 4 | Visibility | 3.4% | 493 |
| 5 | Suspension | 1.5% | 223 |
| 6 | Lighting & signalling | 0.3% | 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 | 6,482 | 5.8% |
| 30-60k | 7,092 | 7.6% |
| 60-90k | 876 | 11.3% |
| 90-120k | 105 | 12.4% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Diesel | 11,164 | 7.2% |
| Hybrid | 2,563 | 6.6% |
| Petrol | 854 | 7.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 464 | 4.3% |
| 2024 | 7,147 | 7.2% |
| 2025 | 6,958 | 7.1% |
What to check before buying a 2021 GLC
On a 2021 GLC, tyres is what the MOT record says goes wrong most — it appeared in 5.2% of tests. Check these areas before you commit.
- Tyres (5.2% 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.
- Visibility (1.1% of tests): Wipers, washers, mirrors and screen damage — usually inexpensive, but check for chips in the driver's line of sight. Typical repair: £15–£150.
- 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 many 2021 Mercedes-Benz GLCs pass their MOT?
92.9% of the 14,581 2021 Mercedes-Benz GLC MOT tests in this dataset passed — a 7.1% fail rate.
What is the most common MOT failure on a 2021 Mercedes-Benz GLC?
Tyres, recorded in 5.2% of tests, followed by visibility (1.1%).
Does the 2021 GLC get worse with mileage?
Its MOT fail rate rises from 5.8% in the 0-30k band to 12.4% in the 90-120k band.
Methodology & source. Based on 14,581 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.