Seat Mii 2018: MOT failure rate for its age
13.9% of 5,080 MOT tests of the Seat Mii first registered in 2018 failed at the first attempt (2019–2024; retests excluded). Against this model's own normal rate at the same ages the index is 94.6 (95% CI 87.7–101.6; 100 = normal for this model at that age): the 2018 build year is no different from other years of the same model at the same age.
| Measure | Value | Unit | Compared with | Years | Tests |
|---|---|---|---|---|---|
| Failed first time | 13.9 | % | all ages tested | 2019–2024 | 5080 |
| Index against this model at the same age (95% CI 87.7–101.6) | 94.6 | index | 100 = normal for this model at that age | 2019–2024 | 5080 |
| Rank among this model's 9 build years | 3 | of 9 | 1 = fails least for its age | 2019–2024 | 5080 |
| Tested in 2024 | 1272 | tests | median 29,856 miles | 2024 | 1272 |
Data release dvsa-2024-v2 (24 Sep 2026) · page updated 30 Sep 2026 · full dataset (v5).
How does the 2018 Seat Mii fail at each age?
Cars built in 2018 were tested at ages 3 to 6 between 2019 and 2024. Each row compares their first-time failure share with what this model normally shows at that age, after allowing for the overall failure level of each test year.
| Age | Tests | Failed, % | 95% interval | Normal for this model at that age, % | Index (100 = normal) |
|---|---|---|---|---|---|
| 3 | 1,279 | 10.9 | 9.3–12.7 | 10.3 | 105.6 |
| 4 | 1,268 | 14.4 | 12.5–16.4 | 14.5 | 98.8 |
| 5 | 1,261 | 15 | 13.1–17.1 | 16.3 | 92.1 |
| 6 | 1,272 | 15.6 | 13.7–17.7 | 17.9 | 87.2 |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 5,080 (initial tests) · Method: normal rate = this model's first-time failure share at that age across its build years (cells of 400+ tests), adjusted for each test year's overall level; cells of 30+ tests, under 500 marked rough · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV
What fails most on the 2018 Seat Mii?
The most common failure group on cars built in 2018 is visibility: 6.5 items per 100 first tests, against 6.1 across all build years of the Seat Mii. These counts are not age-adjusted: cars built in 2018 were tested at ages 3 to 6.
| Failure group | Built 2018, per 100 | All build years, per 100 | Items |
|---|---|---|---|
| Visibility | 6.5 | 6.1 | 333 |
| Tyres | 4.3 | 5 | 218 |
| Lamps, reflectors and electrical equipment | 2.7 | 4.5 | 138 |
| Brakes | 2 | 7.1 | 103 |
| Noise, emissions and leaks | 0.9 | 2.3 | 44 |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 5,121 (initial tests of this build year) · Method: failure items grouped by DVSA's top-level defect groups, per 100 initial tests; groups with 30+ items · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV
How does 2018 compare with the years around it?
Among the 9 published build years of the Seat Mii, 2018 ranks 3 (1 = fails least for its age). 2017: index 94.9. 2019: index 76.8.
| Build year | Index (100 = normal) | 95% interval | Verdict | Tests |
|---|---|---|---|---|
| 2012 | 107.5 | 103.5–111.5 | worse | 10,713 |
| 2013 | 105.7 | 102.8–108.6 | worse | 21,297 |
| 2014 | 92.0 | 89.0–95.0 | better | 18,739 |
| 2015 | 100.0 | 96.5–103.5 | no different | 16,223 |
| 2016 | 108.2 | 103.9–112.5 | worse | 13,470 |
| 2017 | 94.9 | 89.4–100.4 | no different | 7,777 |
| 2018 | 94.6 | 87.7–101.6 | no different | 5,080 |
| 2019 | 76.8 | 69.4–84.2 | better (rough estimate) | 3,992 |
| 2020 | 104.9 | 80.7–129.2 | no different (rough estimate) | 559 |
Source: DVSA MOT bulk data · Window: 2019–2024 · n = 97,850 (initial tests) · Method: observed failures against those expected for the same model at the same ages, test-year level adjusted; verdict follows the printed one-decimal bound · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV
How to cite this page
MOT Risk Index (2026). Seat Mii 2018 MOT statistics (data release dvsa-2024-v2; full dataset motriskindex-families-2024-v5, DOI 10.5281/zenodo.22975051), updated 30 September 2026. motriskindex.co.uk/cars/seat-mii/2018/
How every figure is calculated: methodology. Age, test year and build year are tied together (age = test year − build year), so the test-year level is taken as observed, not estimated.
Other pages for this model
Seat Mii 2012 · Seat Mii 2013 · Seat Mii 2014 · Seat Mii 2015 · Seat Mii 2016 · Seat Mii 2017 · Seat Mii 2019 · Seat Mii 2020 · Seat Mii in Norway · Seat Mii in Finland · Seat Mii in the Netherlands · Seat Mii by postcode area · Seat Mii body, chassis and structure failures · Seat Mii brakes failures · Seat Mii vehicle identification failures · Seat Mii lamps, reflectors and electrics failures · Seat Mii noise, emissions and leaks failures · Seat Mii road wheels failures · Seat Mii seat belts and airbags failures · Seat Mii steering failures · Seat Mii suspension failures · Seat Mii tyres failures · Seat Mii visibility failures