2021 Mercedes-Benz GLC 300 AMG Line Prem + D 4M A MOT pass rate: 91.8% (1,808 tests)
Is the 2021 GLC 300 AMG Line Prem + D 4M A getting worse?
Pass rate of 2021-registered cars across recent test years:
| Test year | Pass rate | |
|---|---|---|
| 2024 | 91.9% +1.2 vs same-age |
|
| 2025 | 91.6% +1.4 vs same-age |
The raw rate normally falls as cars age. The “vs same-age” figure compares this cohort with all UK cars registered in the same year, so normal ageing is not mistaken for a bad model year.
What fails on a 2021 GLC 300 AMG Line Prem + D 4M A
| # | System | Defects recorded | Share |
|---|---|---|---|
| 1 | Tyres | 165 | 72.4% |
| 2 | Brakes | 31 | 13.6% |
| 3 | Visibility | 12 | 5.3% |
| 4 | Lamps, reflectors and electrical equipment | 7 | 3.1% |
| 5 | Suspension | 4 | 1.8% |
| 6 | Noise, emissions and leaks | 4 | 1.8% |
All GLC 300 AMG Line Prem + D 4M A years compared
| Registration year | Tests | Pass rate | Vs same-age | Median mileage |
|---|---|---|---|---|
| 2019 | 3,157 | 91.1% | +2.7 pts | 40,537 |
| 2020 | 5,016 | 91.9% | +2.0 pts | 32,986 |
| 2021 (this page) | 1,808 | 91.8% | +1.3 pts | 31,649 |
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FAQs
Is a 2021 Mercedes-Benz GLC 300 AMG Line Prem + D 4M A reliable?
2021-registered examples passed 91.8% of their MOT tests (1,808 tests, 2023–2025), +1.3 points versus all UK cars registered in the same year. At roughly 5 years old with a median 31,649 miles, condition now varies car by car — always check the individual MOT history.
What mileage is too high for a 2021 GLC 300 AMG Line Prem + D 4M A?
The median tested example shows 31,649 miles. Anything far beyond that isn't automatically bad — a motorway-mile car with consistent service records often beats a low-mileage school-run car — but price accordingly and scrutinise the mileage trail for gaps or drops.
Source: DVSA Anonymised MOT tests and results, 2023–2025 extracts (96 million Class 4 initial tests; retests excluded). Only vehicles old enough for a routine first MOT are included. Age-adjusted figures compare the model-year cohort with all vehicles of the same registration year tested in the same calendar year. Contains public sector information licensed under OGL v3.0.