2020 Mercedes-Benz GLS — MOT failures & pass rate
Across 1,356 MOT tests analysed for the 2020 Mercedes-Benz GLS, the most common recorded failure areas were tyres, lighting & signalling and brakes. Its pass rate of 89.0% was below the average for cars of a similar age (90.6%). Higher-mileage examples failed more often — 21.2% in the 90-120k group versus 9.0% in the 0-30k group.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.6% | 103 |
| 2 | Lighting & signalling | 1.5% | 20 |
| 3 | Brakes | 1.2% | 16 |
| 4 | Suspension | 1.1% | 15 |
| 5 | Seat belts & restraints | 0.9% | 12 |
| 6 | Other defects | 0.7% | 10 |
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 | 49 |
| 2 | Registration plates | 17 |
| 3 | Ball joint | 17 |
| 4 | Brake pads | 14 |
| 5 | Headlamp aim | 11 |
| 6 | Individual direction indicators | 9 |
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 | 18.0% | 244 |
| 2 | Brakes | 8.8% | 119 |
| 3 | Other defects | 6.1% | 83 |
| 4 | Suspension | 3.4% | 46 |
| 5 | Visibility | 2.5% | 34 |
| 6 | Lighting & signalling | 0.9% | 12 |
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 | 476 | 9.0% |
| 30-60k | 662 | 10.9% |
| 60-90k | 181 | 14.4% |
| 90-120k | 33 | 21.2% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 434 | 8.8% |
| 2024 | 461 | 12.6% |
| 2025 | 435 | 11.5% |
What to check before buying a 2020 GLS
Before buying a 2020 Mercedes-Benz GLS, focus on the areas it most often fails on. Tyres accounted for 7.6% of tests for this year.
- Tyres (7.6% 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.
- Lighting & signalling (1.5% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (1.2% 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 2020 Mercedes-Benz GLSs pass their MOT?
89.0% of the 1,356 2020 Mercedes-Benz GLS MOT tests in this dataset passed — a 11.0% fail rate.
What is the most common MOT failure on a 2020 Mercedes-Benz GLS?
Tyres, recorded in 7.6% of tests, followed by lighting & signalling (1.5%).
Does the 2020 GLS get worse with mileage?
Its MOT fail rate rises from 9.0% in the 0-30k band to 21.2% in the 90-120k band.
Methodology & source. Based on 1,356 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-01. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.