2015 SEAT Mii — MOT failures & pass rate
15,461 MOT tests on the 2015 SEAT Mii are in this dataset, and 86.4% of them passed. All cars of a similar age fail 16.5% of the time, so this is 2.9pp better than the group it competes with. Failures cluster in lighting & signalling, brakes and visibility.
What the MOT record shows
No single area dominates — lighting & signalling (6.9%) and brakes (4.3%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are catalyst emissions, position lamp and wipers — catalyst emissions alone was recorded 742 times.
Mileage is the strongest signal on the record: 8.3% of 0-30k cars fail, rising to 27.3% once past 120-150k — 3.3× the risk.
Tyres is the most common advisory, noted on 24.8% of tests — work that passed today but is likely due soon.
The trend is worsening — 11.0% of tests failed in 2021 against 16.7% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 6.9% | 1,063 |
| 2 | Brakes | 4.3% | 671 |
| 3 | Visibility | 3.5% | 546 |
| 4 | Tyres | 3.5% | 540 |
| 5 | Emissions & environmental | 2.4% | 367 |
| 6 | Body, structure & corrosion | 2.2% | 339 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Catalyst emissions | 742 |
| 2 | Position lamp | 567 |
| 3 | Wipers | 469 |
| 4 | Service brake performance | 413 |
| 5 | Headlamp aim | 409 |
| 6 | Tread depth | 327 |
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 | 24.8% | 3,830 |
| 2 | Brakes | 15.8% | 2,449 |
| 3 | Suspension | 7.3% | 1,133 |
| 4 | Other defects | 7.1% | 1,094 |
| 5 | Visibility | 2.9% | 442 |
| 6 | Body, structure & corrosion | 1.2% | 190 |
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 | 3,683 | 8.3% |
| 30-60k | 7,974 | 12.7% |
| 60-90k | 3,026 | 19.2% |
| 90-120k | 631 | 24.7% |
| 120-150k | 121 | 27.3% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 3,022 | 11.0% |
| 2022 | 3,050 | 11.2% |
| 2023 | 3,086 | 13.6% |
| 2024 | 3,122 | 15.3% |
| 2025 | 3,181 | 16.7% |
What to check before buying a 2015 Mii
The failure pattern for this year is specific enough to inspect against: lighting & signalling accounted for 6.9% of tests. Start there.
- Lighting & signalling (6.9% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (4.3% 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 (3.5% 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 2015 SEAT Miis pass their MOT?
86.4% of the 15,461 2015 SEAT Mii MOT tests in this dataset passed — a 13.6% fail rate.
What is the most common MOT failure on a 2015 SEAT Mii?
Lighting & signalling, recorded in 6.9% of tests, followed by brakes (4.3%).
Does the 2015 Mii get worse with mileage?
Its MOT fail rate rises from 8.3% in the 0-30k band to 27.3% in the 120-150k band.
Methodology & source. Based on 15,461 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.