FIGURE 1 // WHERE IT WEARSSeat Mii
Top three failure systems, annotated from 148 failed first-time tests. Arrows point to where the defect is found on the car.
A Seat Mii's brakes barely fail; its tyres pick up the bill
1,415 inspections in a single year make the MII a modestly documented electric car in the data. Tyres cause 50.6% of its failures; tyres take 2.1× the share they take on petrol and diesel cars of the same age.
First-time test findings
The three-year vs four-year picture
AT THREE YEARS OLD10.9%
MII failure rate. Petrol cars of the same age fail 8.2%.
AT FOUR YEARS OLD8.6%
MII failure rate, against 8.9% for petrol.
At three years old the Seat Mii fails 10.9% of the time, over the 8.2% of a petrol car the same age. By 3 years that reaches 10.9%. Tyres cause 50.6% of its failures.
FIGURE 2 // TYRE SECTION91 certificates in 2024
The tyre that wears from the inside
Tyres take 50.6% of the defects that fail this car, 2.1× the share seen on petrol and diesel cars of the same age. The most common item in that group is "A tyre seriously damaged", recorded 91 times in 2024.
SECTION // TYRES CONCENTRATIONYear 3 crossover
Where the curve bends
The crossover with petrol happens around year 3. From there the MII's failure rate climbs faster than the petrol fleet, and the defect list explains why.
Source: DVSA MOT defect items, 2024 test year.
What to check
Check tyre age and tread across the full width, inner edge included. Electric cars wear tyres faster; a cheap mismatched set on a used car tells you how it was run. Have the suspension joints, bushes and springs checked on a lift. On this car it is a leading cause of failure and it is not visible from the outside. Check the washers reach the screen. It fails the test and it is a thirty-second check. Ask for the full MOT history by registration on the free DVSA service: advisories are next year's failures.
3 inspection points:
✓ Tyre inner-edge wear and age
✓ Suspension joints and bushes on a lift
✓ Washer reach
FIGURE 3 // FAILURE RATE BY AGEvs petrol, diesel and all electric cars
Points hidden where fewer than 50 cars of that age were tested. Dashed lines are the same-age petrol and diesel fleets.
Data sheet
- Inspections
- 1,415
- Passed
- 1,237
- Failed
- 148
- Passed after repair
- 30
- Failure rate
- 10.5% (all EV 12.0%)
- Average age
- 3.2 years
- Best year
- 4 yrs · 8.6%
- Worst year
- 3 yrs · 10.9%
- Top cause
- Tyres 50.6%
TABLE 1 // WHAT FAILS, BY SYSTEMshare of failing defects
| System | This car (mark = petrol/diesel) | Share | vs petrol/diesel |
|---|---|---|---|
| Tyres | 50.6% | 2.1× more | |
| Suspension | 24.3% | 1.8× more | |
| Brakes | 2.8% | 6.7× less | |
| Visibility | 10.8% | in line | |
| Lighting | 8.0% | 2.1× less | |
| Steering | 0.4% | 7.8× less | |
| Body | 0.4% | 10.2× less |
TABLE 2 // TOP DEFECTS ON THE CERTIFICATE
- A tyre seriously damaged91
- A suspension pin, bush or joint excessively worn35
- A shock absorber damaged to the extent that it does not function or showing signs of severe leakage14
- Tyre tread depth not in accordance with the requirements12
- Windscreen washers not working or not providing sufficient fluid to clear the windscreen12
- A tyre has a lump, bulge or tear caused by separation or partial failure of its structure. This includes any lifting of the tread rubber11
Wording as printed by the tester, from the DVSA inspection manual.
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Where it holds up
- Brakes fail less often than on petrol and diesel cars (2.8% of defects vs 18.7%)
- Lighting fail less often than on petrol and diesel cars (8.0% of defects vs 16.5%)
- Steering fail less often than on petrol and diesel cars (0.4% of defects vs 3.1%)
- Body fail less often than on petrol and diesel cars (0.4% of defects vs 4.1%)
Where it fails
- Tyres take a bigger share of failures than on petrol and diesel cars of the same age (50.6% vs 23.7%)
- Suspension take a bigger share of failures than on petrol and diesel cars of the same age (24.3% vs 13.6%)
- At three years old it fails 10.9% of the time, above the 8.2% of petrol cars the same age
VERSIONS SEEN IN THE TESTSas recorded
- MII EV1,414
- MII1
OWNER REPORTS // MATCHED TO RECORDED DEFECTS0 read · 0 matched
No owner discussion has been matched to this car's recorded defects yet. Reports are re-collected every quarter; the figures on this page do not depend on them.
Summaries written by us, never quotes; every entry links to its source. Owner reports have no denominator and never feed the failure rate.
SIMILAR CARS IN THE DATAclosest rate and age, other brands
Three things the data shows
- 1,415 inspections in 2024 make this one of the adequately-documented electric cars in the data.
- Tyres take 2.1× the share of failures they take on petrol and diesel cars of the same age.
- Failure rate rises from 8.6% at 4 years to 10.9% at 3: a gentle ageing curve.
LIMITS // WHAT THE INSPECTION DOES NOT TELL YOU
No battery health, no motor, no charging performance. The test covers brakes, suspension, steering, tyres, lights, visibility and structure. A car with a badly degraded battery passes as long as it stops and steers. Read this page as evidence about the chassis, not the powertrain. Cars are tested from their third year, so the newest model years are missing; every figure carries its sample size for that reason. Full methodology.
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