2012 SEAT Mii — MOT failures & pass rate
10,586 MOT tests on the 2012 SEAT Mii are in this dataset, and 82.8% of them passed. All cars of a similar age fail 21.7% of the time, so this is 4.5pp better than the group it competes with. Failures cluster in lighting & signalling, brakes and seat belts & restraints.
What the MOT record shows
No single area dominates — lighting & signalling (8.0%) and brakes (6.3%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are srs malfunction indicator lamp, service brake performance and headlamp aim — srs malfunction indicator lamp alone was recorded 524 times.
A 150k+ example is materially riskier than a 0-30k one: 25.3% versus 8.8%.
Advisories point at the next bill rather than this one: tyres was flagged on 24.9% of tests without failing them.
The trend is worsening — 16.2% of tests failed in 2021 against 18.9% in 2025, the usual pattern as a fleet ages.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Lighting & signalling | 8.0% | 848 |
| 2 | Brakes | 6.3% | 666 |
| 3 | Seat belts & restraints | 5.3% | 565 |
| 4 | Tyres | 3.7% | 391 |
| 5 | Visibility | 3.6% | 379 |
| 6 | Suspension | 3.1% | 324 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | SRS malfunction indicator lamp | 524 |
| 2 | Service brake performance | 482 |
| 3 | Headlamp aim | 387 |
| 4 | Tread depth | 282 |
| 5 | Registration plate lamp(s) | 240 |
| 6 | Wipers | 230 |
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 | 24.9% | 2,631 |
| 2 | Brakes | 18.6% | 1,970 |
| 3 | Other defects | 10.3% | 1,093 |
| 4 | Suspension | 10.3% | 1,090 |
| 5 | Body, structure & corrosion | 3.5% | 369 |
| 6 | Visibility | 3.3% | 344 |
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 | 975 | 8.8% |
| 30-60k | 4,035 | 15.1% |
| 60-90k | 3,656 | 19.0% |
| 90-120k | 1,484 | 22.2% |
| 120-150k | 341 | 24.3% |
| 150k+ | 95 | 25.3% |
Failure rate by age
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 2,134 | 16.2% |
| 2022 | 2,076 | 14.7% |
| 2023 | 2,143 | 17.7% |
| 2024 | 2,143 | 18.6% |
| 2025 | 2,090 | 18.9% |
What to check before buying a 2012 Mii
On a 2012 Mii, lighting & signalling is what the MOT record says goes wrong most — it appeared in 8.0% of tests. Check these areas before you commit.
- Lighting & signalling (8.0% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (6.3% 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.
- Seat belts & restraints (5.3% of tests): Belt damage or faulty pretensioners — usually straightforward but safety-critical. Typical repair: £50–£300.
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 2012 SEAT Miis pass their MOT?
82.8% of the 10,586 2012 SEAT Mii MOT tests in this dataset passed — a 17.2% fail rate.
What is the most common MOT failure on a 2012 SEAT Mii?
Lighting & signalling, recorded in 8.0% of tests, followed by brakes (6.3%).
Does the 2012 Mii get worse with mileage?
Its MOT fail rate rises from 8.8% in the 0-30k band to 25.3% in the 150k+ band.
Methodology & source. Based on 10,586 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.