MOT performance
Audi A3 vs Mercedes-Benz A-Class: MOT pass rates compared
In 2023–2024, 75.0% of 855,563 Audi A3 MOT tests and 78.8% of 685,711 Mercedes-Benz A-Class tests passed first time — 3.8 points in favour of the Mercedes-Benz A-Class. Once age, mileage and fuel are allowed for, the Audi A3 fails less often than the Mercedes-Benz A-Class: 0.81× against 0.94× the national rate for comparable cars.
855,563 Audi A3 and 685,711 Mercedes-Benz A-Class MOT tests, 2023–2024
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| Figure | Value | Basis |
|---|---|---|
| Audi A3: first-time pass rate | 75.0% | ±0.1 pts (95%), n = 855,563 |
| Mercedes-Benz A-Class: first-time pass rate | 78.8% | ±0.1 pts (95%), n = 685,711 |
| Audi A3: failures vs similar cars | -19% | same age, mileage and fuel = 1.00 |
| Mercedes-Benz A-Class: failures vs similar cars | -6% | same age, mileage and fuel = 1.00 |
| Audi A3: dangerous defect | 8.2% | n = 855,563 |
| Mercedes-Benz A-Class: dangerous defect | 7.1% | n = 685,711 |
| Average age at test | 9.6 vs 7 years | Audi A3 vs Mercedes-Benz A-Class |
Why the raw pass rates can mislead
The Audi A3 was tested at an older average age (9.6 years against 7), and older cars fail more often whatever they are. That is why the table above also shows failures against cars of the same age, mileage and fuel: it compares the models, not their fleets. Here the adjustment reverses the raw result: the Audi A3 has the lower pass rate but fails less often than comparable cars.
Failure areas side by side
Share of MOT tests that failed on each area, and in brackets how that compares with cars of the same age, mileage and fuel (1.00 = national average). The clearest difference is seat belts and airbags, where the Mercedes-Benz A-Class fails 2.9 times as often on an adjusted basis.
| Area | Audi A3 | Mercedes-Benz A-Class |
|---|---|---|
| Brakes | 5.6% (-26%) | 4.1% (-15%) |
| Steering | 0.4% (-81%) | 0.2% (-82%) |
| Suspension | 8.3% (-18%) | 4.5% (-18%) |
| Tyres | 7.6% (+8%) | 7.0% (+17%) |
| Road wheels | 0.3% (-28%) | 0.5% (+77%) |
| Lights, reflectors and electrical | 8.0% (-35%) | 5.7% (-23%) |
| Body, chassis and structure | 2.9% (-25%) | 1.2% (-41%) |
| Driver's view of the road | 3.0% (-38%) | 3.8% (-4%) |
| Noise, emissions and leaks | 3.1% (-10%) | 2.1% (+1%) |
| Seat belts and airbags | 1.0% (-10%) | 1.7% (+163%) |
| Registration plates and VIN | 0.4% (+2%) | 0.4% (+35%) |
| Speedometer and driving controls | 0.0% (-37%) | 0.0% (-66%) |
Pass rate at the same age
Comparing cars of the same age removes most of the fleet-age effect from the raw rates.
| Age at test | Audi A3 | Mercedes-Benz A-Class |
|---|---|---|
| 3-4 years | 88.8% (n = 79,035) | 87.4% (n = 164,450) |
| 5-6 years | 86.6% (n = 120,896) | 82.8% (n = 159,737) |
| 7-8 years | 82.8% (n = 157,176) | 77.0% (n = 127,864) |
| 9-10 years | 76.3% (n = 133,447) | 71.1% (n = 75,149) |
| 11-12 years | 67.0% (n = 99,456) | 68.3% (n = 27,588) |
| 13-15 years | 61.9% (n = 136,168) | 61.8% (n = 40,901) |
| 16+ years | 56.9% (n = 98,315) | 57.3% (n = 39,272) |
Most common failure item
- Audi A3 · coil spring: fractured or broken (3.13% of tests)
- Mercedes-Benz A-Class · tread depth: tread depth below requirements of 1.6mm (2.34% of tests)
MOT results reflect how cars are maintained as well as how they are built, so a gap between two models is a difference in test performance, not proof that one is more reliable. For one car, its own MOT history says more than any average.
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About this data. These are MOT test results, not a measure of mechanical reliability: a car's MOT outcome reflects its condition on the day, which depends on how it has been maintained and driven as well as how it was built. Figures cover class 4 vehicles (cars and light vans), normal tests only (retests excluded), outcomes pass, fail and pass after rectification at the station; vehicles at least 2.5 years old at test. Tests from 2023-01-01 to 2024-12-30. “Compared with similar cars” means compared with the national rate for cars of the same age, mileage band and fuel. Contains public sector information licensed under the Open Government Licence v3.0. Makes and models are matched to 73 Auto's vehicle catalogue; tests that can't be matched are left out rather than guessed. See how the MOT figures are produced.