SEAT Mii Reliability: Common Problems and Years to Avoid
What the SEAT Mii fails its MOT on, with rough repair costs, and how each model year's MOT pass rate compares with other cars of the same age. Based on 27,739 MOT tests across 8 model years (DVSA data for tests carried out in 2024, retests included).
Segment: city car | Fuel: Petrol
85%
SEAT Mii pass rate
85%
SEAT average
82%
All-model average
The SEAT Mii has an average MOT pass rate of 85%, which is equal to the SEAT average and 3 points above the average across all models in our data. Newer SEAT Miis pass their MOT more often than older ones, by 6 percentage points on average, which is mostly down to age and wear.
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What the SEAT Mii Fails Its MOT On
Of the 4,315 MOT tests on the SEAT Mii that failed at the first attempt in 2025, the share that failed on each part of the test, next to the share for all cars and vans of the same ages. A test that failed on two areas counts in both.
Lights and electrics
37%Cars and vans the same age: 35% · Typical repair £15-£200
Brakes
25%Cars and vans the same age: 21% · Typical repair £80-£450
Suspension
20%Cars and vans the same age: 32% (the Mii fails on this less often) · Typical repair £150-£600
Tyres
17%Cars and vans the same age: 24% (the Mii fails on this less often) · Typical repair £50-£300
Windscreen, wipers and mirrors
14%Cars and vans the same age: 14% · Typical repair £10-£350
The 3 single faults it failed on most
- Position lamp: not working (8.9% of failed tests, lights and electrics)
- Registration plate lamp(s): inoperative in the case of a single lamp or all lamps (7.8% of failed tests, lights and electrics)
- Headlamp aim: too low (7.1% of failed tests, lights and electrics)
Source: CarCostCheck analysis of DVSA anonymised MOT test results and failure items for 2025: first attempt at each MOT, fail and pass-after-repair defects, DVSA's defect categories (names shortened). Repair costs are rough UK ranges, not quotes. Method and national figures: MOT failure reasons 2025.
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SEAT Mii Years to Avoid
Every car in the 2024 MOT data was tested at the same age as the other cars first registered that year, so each Mii year is compared with all cars from the same year. Years with 1,000+ tests that were at least three years old are included.
Failed more often than cars their age
No year passed 3 or more points less often than other cars of the same age.
Passed more often than cars their age
No year passed 3 or more points more often than other cars of the same age.
A lower pass rate means that year failed its MOT more often in 2024; it does not mean every car from that year is bad. Old cars still on the road are often the best-kept ones, which can lift the pass rates of the oldest years. How a car has been looked after matters more, so check the MOT history of the car you are looking at.
SEAT Mii Reliability by Year
MOT pass rate for each model year, from DVSA data for tests carried out in 2024 (retests included). Newer cars usually pass more often simply because they are younger. All Cars is the pass rate of every car first registered that year, with the gap in points. Highest and lowest are marked among years with 100+ tests that were at least three years old when tested. Fuel and engine size are a guide only.
SEAT Mii Running Costs
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SEAT Mii FAQ
What are the most common SEAT Mii problems?
In 2025, MOT tests on the SEAT Mii that failed at the first attempt most often failed on lights and electrics (37% of the 4,315 failed tests), brakes (25%) and suspension (20%). The single most common fault was "Position lamp: not working" (8.9%). Across 27,739 MOT tests (DVSA MOT data for tests in 2024, retests included), 85% ended in a pass.
Is the SEAT Mii reliable?
The SEAT Mii has an average MOT pass rate of 85%, from 27,739 MOT tests (DVSA MOT data for tests in 2024, retests included). Comparing each model year with all cars first registered the same year, so that age is allowed for, it passed within 1 point of other cars of the same age, so about average for its age.
Which SEAT Mii years should I avoid?
No SEAT Mii year with 1,000+ tests passed 3 or more points less often than all cars first registered the same year (DVSA MOT data for tests in 2024, retests included). A year's pass rate does not tell you about one car, so check the MOT history of the car you are buying.
How much does it cost to fix common SEAT Mii faults?
As a rough guide, brake work on a SEAT Mii typically costs £80-£450 and suspension repairs £150-£600, while exhaust and emissions fixes can cost £80-£800. Lighting and wiper fixes are usually under £200.
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Other SEAT Models
Common problems pages for other SEAT models