SEAT
27,741 MOT tests analysed. sits above the UK fleet average — here's where Miis pass, fail, and end up on the retest sheet.
That's 2.8 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
80.3%
Pass-after-fix
4.6%
Fail
14.7%
Avg miles
53,589
Pass + Pass-after-fix + Fail = 100%
Trim variants
Performance by cohort
2 year bands · 27,739 tests
Pass rate climbs 7.9 points across the cohorts — newer Mii examples clear the test more reliably than the early cars.
Pass
79.4%
Fail
15.6%
PRS
4.6%
Avg mileage at test
56,541 mi
Pass
87.4%
Fail
7.4%
PRS
4.7%
Avg mileage at test
29,321 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
The SEAT Mii is a petrol-powered car sold in the UK market across multiple generations, covering a broad date range in the test population.
MOT data from 20,012 tests puts this car on a 81.2% first-time pass rate, above the UK fleet average. Average mileage at test is 47,727 miles. The most common fail item is significant brake effort recorded with no brake applied indicating a binding brake, followed by tyre tread below the legal limit.
Honest John owner records point to gearbox noise or CVT reliability as the recurring problems to check before buying used.
Buyers weighing up a used Mii should treat the failure breakdown as a pre-purchase checklist. The pass rate is reasonable, but the gap between first attempt and a clean sheet narrows with age and mileage.
ABI Insurance Group
A low-group car — among the cheapest to insure in the UK. Lower groups cost less to insure; UK fleet average is around Group 22.
Source: ABI Group Rating Panel · administered by Thatcham Research · groups cover standard variants; performance trims may sit higher. Browse all insurance groups →
2–7
out of 50
Filter failures:
Hide categories
Tick a category to hide it from rankings sitewide. Saved in this browser only.
Significant brake effort recorded with no brake applied indicating a binding brake
488 occurrences · 1.8% of tests
Tyre tread depth not in accordance with the requirements
432 occurrences · 1.6% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
400 occurrences · 1.4% of tests
A suspension pin, bush or joint excessively worn
361 occurrences · 1.3% of tests
Wiper blade missing or obviously not clearing the windscreen
299 occurrences · 1.1% of tests
Fuel system leaking, or missing or ineffective filler cap
236 occurrences · 0.9% of tests
Lambda coefficient outside the default limits or the range specified by the manufacturer
227 occurrences · 0.8% of tests
A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
226 occurrences · 0.8% of tests
An SRS malfunction indicator lamp (MIL) indicates a system malfunction
222 occurrences · 0.8% of tests
Wiper blade defective
216 occurrences · 0.8% of tests
Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.
Worst-case fix budget · top 3 failures
£160–£380
If every one of this Mii's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →
Try the calculator
Build your own retest budget.
Year-band analysis
First-time MOT pass rate split by registration band. A 7.9-point gap between bands means the year you buy SEAT Mii has a real effect on what turns up at the garage.
Best band to buy
87.4%
2018–2020 registration
the 2018–2020 band climbs to 87.4% — a 7.9-point improvement. Tests in this band average 29,321 miles — roughly 27K miles fewer on the clock than the older band. Failures here are mostly wear items: does not clear the windscreen effectively, damaged but not adversely affecting driver's view — the structural issues that drag down older examples don't appear in the top-10 for this band. The stricter post-2018 MOT test rules meant manufacturers had to tighten up emissions and electrical checks, but this band still shows far fewer major failures on suspension and bodywork than the older fleet.
Band to be cautious about
79.4%
Pre-2018 registration
On the older band (pre-2018), the data shows a 79.4% pass rate against a fleet average of 87.4% on the newer band. The main culprits logged at test: excessively binding, tread depth below requirements of 1.6mm, and damaged but not adversely affecting driver's view. Average mileage on test for this band is 56,541 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (87.4% first-time pass). Worst band to avoid: pre-2018 (79.4% pass). That's a 7.9-point spread across 24,731 older tests and 3,008 newer ones — year of build makes a material difference on this model.
Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.
Item 01 · Amazon UK
Digital tyre-tread depth gauge
Five quid for a gauge beats £150 for a retest. UK MOT minimum is 1.6mm — most testers fail anything below 2mm to be safe.
Search Amazon UK
Item 02 · Amazon UK
Bosch Aerotwin wiper blades
Cheap wipers fail the test on smear streaks. Bosch Aerotwins last a winter and clear a screen properly.
Search Amazon UK
My Motor World · affiliate
Affiliate links — small commission, no extra cost to you.
Hycote
Hycote Touch Up Colour Paint Brush Seat Flash Red 12.5ml
£6.59
View at My Motor World →
Hycote
Hycote Seat Black Magic Double Acrylic Spray Paint 150ml
£6.59
View at My Motor World →
Hycote
Hycote Seat Candy White Double Acrylic Spray Paint 150ml
£6.59
View at My Motor World →
Hycote
Hycote Seat Emocion Red Double Acrylic Spray Paint 150ml
£6.59
View at My Motor World →
Click Mechanic · affiliate
Affiliate links — small commission, no extra cost to you.
Mobile mechanic · UK-wide
Book a mechanic at your door.
Fixed-price quotes upfront. No garage needed. Click Mechanic sends a vetted local mechanic to you — home, work, or roadside.
Owner reports · Honest John
Verbatim faults logged by owners on honestjohn.co.uk over recent years. We didn't summarise — these are the words people typed in.
What's good
As well as being affordable and cheap to run, the Mii is also enjoyable to drive and comfortable too. It feels solid and surprisingly refined for such a small car - in fact from behind the wheel it's easy to think you're in a larger hatchback.
Complaint that new SEAT Mii will not easily go into 1st gear. Dealer fobs off the complaint. [Otr 1.5" Cam / 28 Spline / 5.5" Automatic Slack Adjuster | Auto Slack 1.5" -28/5.5" Arm Haldex Style | Otr-10211 The Otr 1-1/2" Cam / 28 Spline / 5. 5" Automatic Slack Adjuster Ensures Expertise Built In™, Being Engineered With High-Performing, Hig...FleetPride](https://www.bing.com/api/v1/mediation/tracking?adUnit=11725462&auId=1c7e6556-52c6-4272-a7be-fe50d2f4c7ac&bdc=pb&bidId=9&bidderId=4&cmExpId=RSV&impId=445797643&impTy=1&ldc=rhf2nc
Report of 2013 SEAT Mii reaching 65,000 miles without having the timing belt replaced or any sign of trouble (though probably wise to change belt now).
Report of owner of 2016 SEAT Mii manual being recommended by the dealer to have a transmission oil change at its 3rd annual service.
Report of failure of the cabin ventilation/heater/aircon fan motor of a SEAT Mii.
Source: honestjohn.co.uk · 4 reports indexed
Recall history
The Mii has 5 official UK vehicle recalls covering defect details, remedies, and affected build dates.
Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.
If you own a Mii and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.
