2020 Mercedes-Benz G-Class — MOT failures & pass rate
Across 1,331 MOT tests, the 2020 Mercedes-Benz G-Class recorded a 93.2% pass rate. Against large SUVs of a similar age (9.3% fail rate), the 2020 G-Class comes out 2.4pp better. Failures cluster in tyres, other defects and lighting & signalling.
What the MOT record shows
No single area dominates — tyres (3.2%) and other defects (2.3%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are registration plates, malfunction indicator lamp and headlamp aim — registration plates alone was recorded 55 times.
Mileage matters less than usual here: the 2020 G-Class fails 5.0% of the time in the 0-30k band and 6.6% at 60-90k, a spread of only 1.6 points.
Tyres is the most common advisory, noted on 11.6% of tests — work that passed today but is likely due soon.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 3.2% | 42 |
| 2 | Other defects | 2.3% | 30 |
| 3 | Lighting & signalling | 1.0% | 13 |
| 4 | Brakes | 0.9% | 12 |
| 5 | Emissions & environmental | 0.9% | 12 |
| 6 | Visibility | 0.8% | 10 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Registration plates | 55 |
| 2 | Malfunction indicator lamp | 12 |
| 3 | Headlamp aim | 11 |
| 4 | Brake pads | 11 |
| 5 | Tread depth | 10 |
| 6 | Wipers | 4 |
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 | 11.6% | 154 |
| 2 | Brakes | 5.8% | 77 |
| 3 | Other defects | 3.5% | 46 |
| 4 | Visibility | 2.9% | 39 |
| 5 | Suspension | 1.9% | 26 |
| 6 | Steering | 0.7% | 9 |
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 | 656 | 5.0% |
| 30-60k | 582 | 8.6% |
| 60-90k | 76 | 6.6% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 904 | 6.5% |
| Diesel | 423 | 7.6% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 427 | 8.0% |
| 2024 | 425 | 5.9% |
| 2025 | 443 | 6.6% |
What to check before buying a 2020 G-Class
The failure pattern for this year is specific enough to inspect against: tyres accounted for 3.2% of tests. Start there.
- Tyres (3.2% 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.
- Other defects (2.3% of tests): Miscellaneous items not in the main categories. Typical repair: varies.
- Lighting & signalling (1.0% 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 2020 Mercedes-Benz G-Classs pass their MOT?
93.2% of the 1,331 2020 Mercedes-Benz G-Class MOT tests in this dataset passed — a 6.8% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz G-Class?
Tyres, recorded in 3.2% of tests, followed by other defects (2.3%).
Does the 2020 G-Class get worse with mileage?
Its MOT fail rate rises from 5.0% in the 0-30k band to 6.6% in the 60-90k band.
Methodology & source. Based on 1,331 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.