Photo: Vauxford, CC BY-SA 4.0
BMW
8,062 MOT tests analysed. sits above the UK fleet average — here's where 420i M Sport Autos pass, fail, and end up on the retest sheet.
That's 15.2 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
92.7%
Pass-after-fix
0.8%
Fail
6.2%
Avg miles
24,063
Pass + Pass-after-fix + Fail = 100%
Petrol cars first registered from January 2006 meet Euro 4 — compliant in London ULEZ, Birmingham CAZ, Bristol CAZ, and Glasgow LEZ.
Performance by cohort
2 year bands · 8,062 tests
Pass rate drops 1.8 points across the cohorts — recent 420i M Sport Auto examples are doing worse than the early cars at the same tested age.
Pass
94.4%
Fail
4.6%
PRS
0.2%
Avg mileage at test
28,653 mi
Pass
92.6%
Fail
6.3%
PRS
0.8%
Avg mileage at test
23,686 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
Across 8,062 MOT tests, the 420i M Sport Auto returns 92.7% first-time pass — comfortably ahead of the UK fleet average. The single most-logged Major fail is a seriously damaged tyre. A seriously damaged tyre and tyre tread under the limit round out the top three. Average tested mileage sits at 24,063, which is the lens to read those failure rankings through. If you own one and the next test is close, the ranked list below is a sensible pre-test checklist.
Filter failures:
Hide categories
Tick a category to hide it from rankings sitewide. Saved in this browser only.
A tyre seriously damaged
151 occurrences · 1.9% of tests
A tyre seriously damaged
109 occurrences · 1.4% of tests
Tyre tread depth not in accordance with the requirements
97 occurrences · 1.2% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
67 occurrences · 0.8% of tests
A tyre cords visible or damaged
61 occurrences · 0.8% of tests
Number plate does not conform to the specified requirements
20 occurrences · 0.2% of tests
Wiper blade defective
18 occurrences · 0.2% of tests
Windscreen washers not working or not providing sufficient fluid to clear the windscreen
17 occurrences · 0.2% of tests
A tyre has a lump, bulge or tear caused by separation or partial failure of its structure. This includes any lifting of the tread rubber
11 occurrences · 0.1% of tests
Any fracture or welding defect on a wheel
8 occurrences · 0.1% 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 2 failures
£120–£190
If every one of this 420i M Sport Auto'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 1.8-point gap between bands is modest — the year you buy BMW 420i M Sport Auto makes a small but real difference to MOT outcomes.
Best band to buy
94.4%
2018–2020 registration
the 2018–2020 band climbs to 94.4% — a 1.8-point improvement. Failures here are mostly wear items: has a bulge, caused by separation or…, has ply or cords exposed — the structural issues that drag down older examples don't appear in the top-10 for this band.
Band to be cautious about
92.6%
2021+ registration
On the 2021-on band, the data shows a 92.6% pass rate against a fleet average of 94.4% on the newer band. The main culprits logged at test: has a bulge, caused by separation or…, has a cut in excess of the…, and tread depth below requirements of 1.6mm. Average mileage on test for this band is 23,686 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (94.4% first-time pass). Worst band to avoid: 2021+ (92.6% pass). That's a 1.8-point spread across 7,450 older tests and 612 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.
My Motor World · affiliate
Affiliate links — small commission, no extra cost to you.
Summit
Summit ADRG-640 BMW Replacement Stick-On Tinted Mirror Glass LHS
£10.99
View at My Motor World →
Summit
Summit ADRG-904 BMW Replacement Stick-On Tinted Mirror Glass RHS
£10.99
View at My Motor World →
Summit
Summit ADRG-905 BMW Replacement Stick-On Tinted Mirror Glass LHS
£10.99
View at My Motor World →
Draper Expert
Draper Expert Oil Filter Socket for Audi, BMW, Mercedes-Benz, Porsche and VW
£18.69
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.
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 420i M Sport Auto 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.