2021 Mercedes-Benz G-Class — MOT failures & pass rate
The 2021 Mercedes-Benz G-Class passed 92.9% of its 1,203 recorded MOT tests. That is 1.8 percentage points better than large SUVs of a similar age, which fail at 8.9%. Failures cluster in tyres, brakes and lighting & signalling.
What the MOT record shows
Tyres dominates the failure mix at 4.4% of all tests — 3.2 points clear of brakes, so it is the first thing to check.
At component level the recurring items are brake pads, tread depth and registration plates — brake pads alone was recorded 22 times.
Condition tracks the odometer closely. Failures run at 4.6% in the 0-30k band and 10.5% in the 60-90k band, a 5.9-point spread — more than double.
Advisories point at the next bill rather than this one: tyres was flagged on 13.9% of tests without failing them.
The trend is improving — the fail rate fell from 10.0% in 2021 to 6.8% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 4.4% | 53 |
| 2 | Brakes | 1.3% | 15 |
| 3 | Lighting & signalling | 0.9% | 11 |
| 4 | Visibility | 0.9% | 11 |
| 5 | Other defects | 0.8% | 10 |
| 6 | Suspension | 0.3% | 3 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Brake pads | 22 |
| 2 | Tread depth | 22 |
| 3 | Registration plates | 20 |
| 4 | Headlamp aim | 15 |
| 5 | Wipers | 8 |
| 6 | Washers | 6 |
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 | 13.9% | 167 |
| 2 | Brakes | 6.7% | 81 |
| 3 | Other defects | 4.2% | 50 |
| 4 | Visibility | 1.8% | 22 |
| 5 | Emissions & environmental | 1.0% | 12 |
| 6 | Suspension | 0.8% | 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 |
|---|---|---|
| 0-30k | 672 | 4.6% |
| 30-60k | 462 | 10.2% |
| 60-90k | 57 | 10.5% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 753 | 7.0% |
| Diesel | 444 | 7.0% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 30 | 10.0% |
| 2024 | 553 | 7.6% |
| 2025 | 591 | 6.8% |
What to check before buying a 2021 G-Class
On a 2021 G-Class, tyres is what the MOT record says goes wrong most — it appeared in 4.4% of tests. Check these areas before you commit.
- Tyres (4.4% 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.
- Brakes (1.3% 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 (0.9% 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
How many 2021 Mercedes-Benz G-Classs pass their MOT?
92.9% of the 1,203 2021 Mercedes-Benz G-Class MOT tests in this dataset passed — a 7.1% fail rate.
What is the most common MOT failure on a 2021 Mercedes-Benz G-Class?
Tyres, recorded in 4.4% of tests, followed by brakes (1.3%).
Does the 2021 G-Class get worse with mileage?
Its MOT fail rate rises from 4.6% in the 0-30k band to 10.5% in the 60-90k band.
Methodology & source. Based on 1,203 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.