At a glance
How 2,366 first tests went in 2025.
- Passed first time
- 79 in every 100
- Did not pass first time
- 21 in every 100496 failed first-attempt tests
- The typical car
- 5 yearsabout 26,500 miles
- First tests counted
- 2,366
What failed most often
- Tyre condition (front)16 in every 100 failed tests
- Headlight aim11 in every 100 failed tests
How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.
These are patterns across 2020 MG 3 vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. A wear pattern follows age and use more than the way the car was built. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.
Brakes
One fault: handbrake efficiency below minimum (roller test), 7.3 times as often as on similar cars.
Figures below are measured across the 494 of 496 failed first attempts (99.6%) that recorded an odometer reading in 2025. Mileage is needed to compare like with like.
We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.
Handbrake efficiency below minimum (roller test)
What it means
A parking brake with efficiency below the minimum requirement is Major, and graded Dangerous where efficiency is less than half of the required value. On a roller brake tester, the requirement counts as met if more than half of the wheels of a brake system lock. The check applies only to vehicles whose parking brake was not already tested as the secondary brake.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Lamps and electrical
One fault and one wear pattern. The strongest is the brake light (rear): 7.3 times as often as on similar cars.
Brake light (rear)
What it means
All stop lamps missing or not working is graded Dangerous, and so is a stop lamp that stays on when the brakes are released. A stop lamp that is missing or not working is Major. On some vehicles with LED rear lamps, part of the stop lamp can go out when the rear fog lamp is lit, which is not regarded as a defect.
Headlight aim (front)
What it means
Beam aim too high, too low or off to either side is Major. Where a driver's beam aim control is fitted, the aim is tested without altering the setting, and rechecked at the highest setting only if it would fail for being too low. Masks or converter kits on right hand dip headlamps are acceptable.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Suspension
One fault: coil spring (rear), 4.1 times as often as on similar cars.
Coil spring (rear)
What it means
A missing bump stop rubber is not a reason to fail a coil spring. When the vehicle is jacked and lowered, a spring that does not correctly locate as the suspension returns to its normal running position is rejected as insecurely attached. A missing spring is Major, and graded Dangerous where directional control is affected.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Tyres
One wear pattern: tyre pressure monitoring system, 2.1 times as often as on similar cars.
Tyre pressure monitoring system
What it means
A tyre pressure monitoring system that is obviously inoperative is graded Major, and so is one listed as malfunctioning or obviously inoperative. The Minor row uses the word malfunctioning too, but its detail is a warning lamp indicating a fault, and it also covers a tyre that is obviously under-inflated.
Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.
Advisories
Other things testers noted as worn or close to failing, more often than on similar cars.
An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail.
Brake discs (front)
Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.
MOT pass rates
How first tests ended, and how the pass rates are counted.
- Passed first time
- 79in every 100
- Passed on the first test.
- Fixed at the station
- 6in every 100
- Failed, then fixed at the test station the same day.
- Failed
- 15in every 100
- Did not pass, and were not fixed at the test station.
First-attempt pass 79.0% of 2,366 first tests (2025): only cars that passed first time count. Official-style pass 85.1%: cars fixed at the test station also count as a pass. The 6 fixed and the 15 not fixed make the 21 in every 100 that did not pass first time.
Same model, other years
Passed first time in every 100, all tested in 2025.
Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 82 in every 100 passed first time.
| Year | Passed first time | First tests |
|---|---|---|
| 2014 | 67 in every 100 | 1,443 |
| 2015 | 65 in every 100 | 2,139 |
| 2016 | 71 in every 100 | 2,888 |
| 2017 | 69 in every 100 | 2,714 |
| 2018 | 72 in every 100 | 2,441 |
| 2019 | 75 in every 100 | 3,477 |
| 2020 This car | 79 in every 100 | 2,366 |
| 2021 | 82 in every 100 | 1,868 |
| 2022 | 85 in every 100 | 3,999 |
If you are buying one
What this year's MOT record means for the decision in front of you.
Mileage matters most on a 2020 MG 3.
Of 2020 MG 3 vehicles with under 17,000 miles, 88 in every 100 passed their 2025 MOT first time. With 39,000 miles or more, 67 in every 100 did.
What to check at your mileage
How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.
| Under 17,000 | 24,000–30,000 | 39,000 and over | |
|---|---|---|---|
| Tyre condition (front) | 2.7 | 3.7 | 1.5 |
| Headlight aim | 0.9 | 1.8 | 3.2 |
Faults per 100 first tests, by the car's mileage at the test.
When a car fails
of failed cars had one item to fix.
of failed cars had three or more items to fix.
of all first tests had a defect the tester marked dangerous (unsafe to drive away).
Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.
FAQs
Short answers about how to read this model-year guide.
About this data
How this page is built and what it can (and can't) say.
These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.
What we include
UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.
Same-day repairs
PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.
How we compare
We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.
What this does not cover
- MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
- Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
- Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
- If the data for a car is too thin to say anything useful, we say so rather than guess.
Contains public sector information licensed under the Open Government Licence v3.0.
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