SEAT Mii MOT pass rate & common failures
Across 10 model years and 101,807 tests, the SEAT Mii passes its MOT 86.5% of the time. That is 3.1 percentage points better than all cars of a similar age, which fail at 16.6%. Its most common failure areas are lighting & signalling, brakes and visibility.
Best and worst Mii years
Ranked across Mii years with at least 1,000 tests. Older cars fail more simply because they are older — compare years close together in age before drawing conclusions.
What the MOT record shows
The strongest year on this record is 2019 (93.2% pass rate); the weakest is 2012 (82.8%). Older cars carry more of the difference than the average implies.
No single area dominates — lighting & signalling (6.3%) and brakes (4.5%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are headlamp aim, service brake performance and wipers — headlamp aim alone was recorded 3,179 times.
A 150k+ example is materially riskier than a 0-30k one: 24.1% versus 7.5%.
The electric cars hold up better: 9.3% fail against 13.6% for petrol, a 4.3-point gap across 101,796 tests.
Tyres is the most common advisory, noted on 24.0% of tests — work that passed today but is likely due soon.
The trend is worsening — 11.5% of tests failed in 2021 against 15.8% in 2025, the usual pattern as a fleet ages.
How it compares
By model year
Every Mii model year with a usable sample. Years with their own detailed report are linked.
| Year | Tests | Pass rate | Fail rate | Most common failure |
|---|---|---|---|---|
| 2012 | 10,586 | 82.8% | 17.2% | Lighting & signalling |
| 2013 | 20,946 | 83.5% | 16.5% | Lighting & signalling |
| 2014 | 17,851 | 86.4% | 13.7% | Lighting & signalling |
| 2015 | 15,461 | 86.4% | 13.6% | Lighting & signalling |
| 2016 | 12,841 | 86.5% | 13.6% | Lighting & signalling |
| 2017 | 8,249 | 89.4% | 10.6% | Visibility |
| 2018 | 6,876 | 91.5% | 8.5% | Visibility |
| 2019 | 5,680 | 93.2% | 6.8% | Lighting & signalling |
| 2020 | 919 | 91.0% | 9.0% | Tyres |
| 2021 | 2,398 | 90.5% | 9.5% | Tyres |
Most common failures (all years)
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 6.3% | 6,466 |
| 2 | Brakes | 4.5% | 4,576 |
| 3 | Visibility | 3.6% | 3,687 |
| 4 | Tyres | 3.5% | 3,568 |
| 5 | Suspension | 2.3% | 2,345 |
| 6 | Body, structure & corrosion | 1.9% | 1,954 |
| 7 | Seat belts & restraints | 1.6% | 1,640 |
| 8 | Emissions & environmental | 1.5% | 1,568 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Headlamp aim | 3,179 |
| 2 | Service brake performance | 3,083 |
| 3 | Wipers | 2,840 |
| 4 | Catalyst emissions | 2,562 |
| 5 | Tread depth | 2,096 |
| 6 | Position lamp | 2,012 |
| 7 | Washers | 1,527 |
| 8 | SRS malfunction indicator lamp | 1,415 |
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 | 24.0% | 24,403 |
| 2 | Brakes | 15.4% | 15,692 |
| 3 | Other defects | 7.1% | 7,231 |
| 4 | Suspension | 7.1% | 7,190 |
| 5 | Visibility | 2.8% | 2,828 |
| 6 | Body, structure & corrosion | 1.6% | 1,648 |
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 | 29,405 | 7.5% |
| 30-60k | 43,714 | 13.1% |
| 60-90k | 21,344 | 18.9% |
| 90-120k | 5,839 | 23.2% |
| 120-150k | 1,220 | 25.7% |
| 150k+ | 270 | 24.1% |
Failure rate by age
By fuel type
| Fuel | Tests | Fail rate |
|---|---|---|
| Petrol | 98,489 | 13.6% |
| Electric | 3,307 | 9.3% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 18,336 | 11.5% |
| 2022 | 19,705 | 11.6% |
| 2023 | 20,265 | 13.2% |
| 2024 | 21,721 | 14.8% |
| 2025 | 21,780 | 15.8% |
What to check before buying a SEAT Mii
- Lighting & signalling (6.3% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (4.5% 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.
- Visibility (3.6% 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.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
What is the MOT pass rate for the SEAT Mii?
86.5% of the 101,807 SEAT Mii MOT tests in this dataset passed, a 13.5% fail rate, across model years 2012–2021.
What does the SEAT Mii most often fail its MOT on?
Lighting & signalling, recorded in 6.3% of tests, then brakes (4.5%).
Which Mii years are best and worst for MOT results?
2019 has the best pass rate at 93.2% and 2012 the weakest at 82.8%, from 5,680 and 10,586 tests respectively.
How much does mileage affect Mii MOT results?
Fail rates run at 7.5% for cars in the 0-30k band and 24.1% for 150k+, a 16.5-point difference.
Is the electric or petrol Mii more reliable at MOT time?
On MOT-testable defects the electric fails 9.3% of the time against 13.6% for the petrol. This covers testable items only, not engine or gearbox reliability.
Methodology & source. Based on 101,807 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.