MOT data by first-use year
2021 Mercedes-Benz GLB: MOT fail rate and common problems
DVSA MOT tests 2022–2025 · 8,260 MOT tests · Updated
10.7% of 2021 Mercedes-Benz GLB cars failed their MOT at 4 years; measured against vehicles the same age and test year, about the same as the 2020 and 2022 cars (8,260 MOT tests) [1].
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- −3.7 to −2.0 points: the gap to all class 4 vehicles the same age and test year, from 3 to 4 years, 8,260 MOT tests
- 30,000 to 60,000 miles: 11.9% of Mercedes-Benz GLB cars first used 2020–2021 failed at 4 years, against 8.2% at under 30,000 miles, 6,277 MOT tests
- At 4 years (tested 2025): 10.7% failed, against 12.7% for all class 4 vehicles tested at 4 years in 2025, 4,131 MOT tests
Engine, fuel and mileage decide where one vehicle sits within these figures. Check the reg first.
Figures are for 2021 Mercedes-Benz GLB cars as a group, not for one car.
- Fail rate at 4 years (2025)
- 10.7%
- vs 12.7% for all class 4 vehicles tested at 4 years in 2025
- 4,131 MOT tests
- Gap to all class 4, same age and year
- −2.9 pts
- over ages 3–4: −3.7 to −2.0 pts
- 8,260 MOT tests
- Against the 2020 and 2022 cars
- −0.8 pts
- 95% range −2.1 to +0.5 pts, same ages, each against its own test year
- 8,260 MOT tests
- MOT tests of 2021 cars
- 8,260
- tested 2024–2025, 2 ages with 1,000+ tests
- 8,260 MOT tests
About the same as the 2020 and 2022 cars: −0.8 points at the same ages (3–4), each year against all class 4 vehicles the same age tested in its own year; 95% range −2.1 to +0.5, from 8,260 MOT tests of 2021 cars and 10,541 of the 2020 and 2022 cars. Not adjusted for mileage.
Every Mercedes-Benz GLB year against all class 4 vehicles the same age
2021 Mercedes-Benz GLB fail rate at each MOT
From 2024 to 2025, as these cars went from 3 to 4 years old, the fail rate went from 8.7% to 10.7%, and the gap to all class 4 vehicles the same age and test year from −3.7 to −2.0 points. The widest gap was at 3 years (−3.7 points, 4,129 MOT tests).
| Test year | Age | Fail rate | 95% range | MOT tests | All class 4, same age and year | Gap |
|---|---|---|---|---|---|---|
| 2024 | 3 years | 8.7% | 7.9%–9.6% | 4,129 | 12.4% | −3.7 pts |
| 2025 | 4 years | 10.7% | 9.8%–11.7% | 4,131 | 12.7% | −2.0 pts |
All class 4: every class 4 vehicle (cars and light vans) tested at that age in the same test year.
2021 against the 2020 and 2022 cars, age by age
| Age | 2021 | Years either side |
|---|---|---|
| 3 years | 8.7% 4,129 MOT tests, tested 2024 | 2020: 10.6% (2,608, tested 2023) 2022: 9.0% (5,309, tested 2025) |
| 4 years | 10.7% 4,131 MOT tests, tested 2025 | 2020: 11.0% (2,624, tested 2024) |
Each year was tested in a different calendar year; the verdict compares each against all class 4 vehicles the same age tested in its own year.
What fails on a Mercedes-Benz GLB at 4 years
All Mercedes-Benz GLB MOTs at 4 years, cars first used 2020–2021 (6,756 MOT tests; DVSA item counts are not split by first-use year). The most common fail items: tyre condition: has a cut in excess of the requirements deep enough to reach the ply or cords (2.9 per 100 MOT tests, a wear item), brake pads under 1.5 mm (1.3 per 100 MOT tests, a wear item) and tyre with cords exposed (1.1 per 100 MOT tests, a wear item).
No item fails at a clearly different rate from all class 4 vehicles the same age across 3 or more ages.
Mileage and the fail rate at 4 years
Mercedes-Benz GLB cars first used 2020–2021 at 30,000 to 60,000 miles failed 11.9% of MOTs at 4 years (3,788 MOT tests), against 8.2% at under 30,000 miles (2,489 MOT tests). All class 4 vehicles: 15.5% and 10.2%.
Car tax and ULEZ for a 2021 car
A car first registered in the UK in 2021 was issued a 70 (January–February), 21 (March–August) or 71 (September–December) plate, unless it was registered in Northern Ireland (no age identifier) or has since moved to a private plate. An imported one is plated when first registered here, so its plate can be newer than its first-use year. 21 plates
A 2021 car pays the standard rate after its first year. If its list price was over £40,000 it pays the expensive car supplement in years 2 to 6 (to 2027). [2] Car tax calculator for a 2021 car
For the London ULEZ, a 2021 petrol usually meets Euro 4, and a 2021 diesel usually meets Euro 6. The Euro standard of the car decides, not the year alone. [3] ULEZ checker
Buying a Mercedes-Benz GLB? Check that exact car before the viewing.
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- Model risks for this year and fuel
- What similar cars did at their next MOT
- Repairs ahead
- Viewing checklist
Questions people ask
What is the MOT fail rate of a 2021 Mercedes-Benz GLB?
10.7% at 4 years (tested 2025), from 4,131 MOT tests, against 12.7% for all class 4 vehicles tested at 4 years in 2025.
Does the 2021 Mercedes-Benz GLB fail more MOTs than the 2020 and 2022?
0.8 percentage points apart at the same ages (3–4), each against all class 4 vehicles the same age and test year, from 8,260 MOT tests (95% range −2.1 to +0.5), so about the same.
At what ages were 2021 Mercedes-Benz GLB cars MOT tested in the data?
2 ages with at least 1,000 MOT tests: 3–4 years, tested 2024–2025, 8,260 MOT tests in all.
What fails most on a Mercedes-Benz GLB at 4 years?
2.9 in 100 MOT tests failed on tyre condition: has a cut in excess of the requirements deep enough to reach the ply or cords, the most common fail item (a wear item). From 6,756 MOT tests of Mercedes-Benz GLB cars first used 2020–2021, not only 2021.
Sources
- Driver and Vehicle Standards Agency, Anonymised MOT tests and results, 2022 to 2025. DVSA MOT data, Open Government Licence v3.0, 8,260 MOT tests. Accessed 7 Oct 2026.
- GOV.UK, Vehicle tax rates. Rules, not drawn from the MOT data.
- Transport for London, Ultra Low Emission Zone. Rules, not drawn from the MOT data.
Cars tested at 4 years are compared with every class 4 vehicle tested at 4 years in the same test year. These rates are not adjusted for mileage. Breakdowns and non-MOT faults are not in this data. How we compare