2020 SEAT Mii — MOT failures & pass rate
Across 919 MOT tests, the 2020 SEAT Mii recorded a 91.0% pass rate. That is effectively the same as all cars of a similar age (9.4% fail rate), so the MOT record here is unremarkable in either direction. Failures cluster in tyres, lighting & signalling and visibility.
What the MOT record shows
One area stands out: tyres, recorded in 7.2% of tests against 2.2% for the next-worst category.
At component level the recurring items are headlamp aim, wipers and tread depth — headlamp aim alone was recorded 16 times.
Tyres is the most common advisory, noted on 18.6% of tests — work that passed today but is likely due soon.
The trend is improving — the fail rate fell from 10.4% in 2023 to 8.8% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Tyres | 7.2% | 66 |
| 2 | Lighting & signalling | 2.2% | 20 |
| 3 | Visibility | 1.2% | 11 |
| 4 | Brakes | 0.8% | 7 |
| 5 | Suspension | 0.5% | 5 |
| 6 | Other defects | 0.3% | 3 |
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 | 16 |
| 2 | Wipers | 13 |
| 3 | Tread depth | 9 |
| 4 | Washers | 5 |
| 5 | Registration plate lamp(s) | 4 |
| 6 | Headlamp | 4 |
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 | 18.6% | 171 |
| 2 | Brakes | 7.2% | 66 |
| 3 | Other defects | 5.5% | 51 |
| 4 | Suspension | 2.3% | 21 |
| 5 | Visibility | 2.2% | 20 |
| 6 | Body, structure & corrosion | 0.2% | 2 |
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 | 765 | 8.6% |
| 30-60k | 147 | 10.9% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2023 | 309 | 10.4% |
| 2024 | 299 | 8.0% |
| 2025 | 308 | 8.8% |
What to check before buying a 2020 Mii
The failure pattern for this year is specific enough to inspect against: tyres accounted for 7.2% of tests. Start there.
- Tyres (7.2% of tests): Usually a quick, known-cost fix, but check tread, age and uneven wear (which can hint at alignment or suspension issues). Typical repair: £50–£120 per tyre.
- Lighting & signalling (2.2% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Visibility (1.2% 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
How many 2020 SEAT Miis pass their MOT?
91.0% of the 919 2020 SEAT Mii MOT tests in this dataset passed — a 9.0% fail rate.
What is the most common MOT failure on a 2020 SEAT Mii?
Tyres, recorded in 7.2% of tests, followed by lighting & signalling (2.2%).
Does the 2020 Mii get worse with mileage?
Its MOT fail rate rises from 8.6% in the 0-30k band to 10.9% in the 30-60k band.
Methodology & source. Based on 919 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.