2021 Mercedes-Benz GLA — MOT failures & pass rate
The 2021 Mercedes-Benz GLA passed 93.5% of its 19,093 recorded MOT tests. Small SUVs of a similar age fail at 7.2%, so the 2021 GLA sits squarely on the average. Failures cluster in tyres, visibility and brakes.
What the MOT record shows
No single area dominates — tyres (3.9%) and visibility (1.5%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are tread depth, wipers and headlamp aim — tread depth alone was recorded 232 times.
Mileage matters less than usual here: the 2021 GLA fails 5.4% of the time in the 0-30k band and 9.1% at 90-120k, a spread of only 3.7 points.
Fuel type barely separates them — diesel fails 6.2% of the time against 6.8% for petrol.
Advisories point at the next bill rather than this one: tyres was flagged on 18.4% of tests without failing them.
The trend is worsening — 4.0% of tests failed in 2023 against 6.4% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 3.9% | 747 |
| 2 | Visibility | 1.5% | 280 |
| 3 | Brakes | 0.9% | 171 |
| 4 | Lighting & signalling | 0.9% | 172 |
| 5 | Seat belts & restraints | 0.6% | 106 |
| 6 | Suspension | 0.5% | 94 |
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 | 232 |
| 2 | Wipers | 224 |
| 3 | Headlamp aim | 165 |
| 4 | Brake pads | 158 |
| 5 | Washers | 88 |
| 6 | Registration plates | 54 |
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 | 18.4% | 3,505 |
| 2 | Brakes | 7.0% | 1,338 |
| 3 | Other defects | 5.6% | 1,075 |
| 4 | Visibility | 3.4% | 642 |
| 5 | Suspension | 0.9% | 166 |
| 6 | Lighting & signalling | 0.2% | 42 |
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 | 10,874 | 5.4% |
| 30-60k | 7,443 | 7.7% |
| 60-90k | 703 | 10.7% |
| 90-120k | 66 | 9.1% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 8,421 | 6.8% |
| Diesel | 7,143 | 6.2% |
| Hybrid | 3,529 | 6.5% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 453 | 4.0% |
| 2024 | 9,412 | 6.8% |
| 2025 | 9,218 | 6.4% |
What to check before buying a 2021 GLA
On a 2021 GLA, tyres is what the MOT record says goes wrong most — it appeared in 3.9% of tests. Check these areas before you commit.
- Tyres (3.9% 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 (1.5% 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 (0.9% 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 GLAs pass their MOT?
93.5% of the 19,093 2021 Mercedes-Benz GLA MOT tests in this dataset passed — a 6.5% fail rate.
What is the most common MOT failure on a 2021 Mercedes-Benz GLA?
Tyres, recorded in 3.9% of tests, followed by visibility (1.5%).
Does the 2021 GLA get worse with mileage?
Its MOT fail rate rises from 5.4% in the 0-30k band to 9.1% in the 90-120k band.
Methodology & source. Based on 19,093 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.