Should I check the MOT history before buying a 2021 BMW 420i M Sport Auto?

Yes. Look for recurring advisories — slow-building issues like corrosion or brake wear patterns show up years before they become failures. A full MOT history analysis will highlight patterns that a single test result won't reveal.

What corrosion should I look for when inspecting a 2021 BMW 420i M Sport Auto?

Check brake pipes, sills, subframes, and chassis legs. Surface rust is normal at this age; structural rust is a serious problem that is expensive to fix and can fail an MOT.

How are tyres and brakes typically on a 2021 BMW 420i M Sport Auto?

Tyres and brakes are the most common advisory items on vehicles of this age. Budget for replacement if they are near the limit, and factor this into your offer price.

Is the 2021 BMW 420i M Sport Auto reliable?

Based on MOT data from 2,836 vehicles, the 2021 BMW 420i M Sport Auto has a first-time MOT pass rate of 92.6%, indicating generally reliable for its class. Always check the full MOT history of any specific vehicle before buying.

Do I need an HPI check when buying a 2021 BMW 420i M Sport Auto?

Yes. The MOT history will not show outstanding finance, insurance write-offs, or stolen status. An HPI check covers these areas and should be part of any used car purchase.

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BMW 420i M Sport Auto (2021)

2,836 real MOT outcomes analysed • 92.6% first-time pass rate

2021 BMW 420i M Sport Auto

CarHunch analysed 2,836 real MOT records for the 2021 BMW 420i M Sport Auto. Real test outcomes — pass rates, defect profiles, mileage data — from verified DVLA records. Updated as new MOTs are recorded.
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AI Analysis Reliability Overview Check a Specific Reg Buyer's Checklist Pass Rate by Fuel Mileage Distribution Still on the Road MOT Averages Colour Breakdown Compare Models

The 2021 BMW 420i M Sport Auto is a notably reliable proposition, passing its MOT first time in 90.4% of cases—well above the UK average of 80%—and just 12.3% of vehicles have ever recorded a dangerous defect, which is reassuringly low. At 25,466 miles median (27,364 average), these cars are still relatively young and lightly used for their age, which explains why owners are averaging only 0.23 failures per vehicle and mostly encountering minor advisories rather than serious problems.

The real-world upshot is straightforward: this generation 420i is holding up well through its early years, and petrol versions (90.2% pass rate) are performing consistently across the board. When buying, get a pre-purchase inspection done anyway—not because this model is risky, but because catching that 1 in 5 advisory item early will save you money down the line.

The 2021 BMW 420i M Sport Auto passes its MOT first time more often than most UK vehicles (92.6% vs ~80% average) — and when it does fail, it's usually something minor and cheap to fix.

⚠️ Around 1 in 8 of these vehicles have had a dangerous MOT failure at some point — usually tyres or brakes, and often a one-off issue rather than a persistent problem. The group stats won't tell you which one you're looking at.

First-time pass

92.6%

UK average ~80%

Better than average

Dangerous (ever)

12.3%

At least once in MOT history

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Avg failures / car

0.23

Over 2.3 tests on record

Low

Typical mileage

25k

Middle half: 18k–34k

For context

✅ Good baseline reliability. A 92.6% first-time pass rate puts this well above the UK average — it's a well-sorted vehicle in this age bracket.

🔍 The dangerous defect figure is real. Most are one-off tyre failures or brake issues — not structural problems. But it's exactly why checking the individual vehicle's history is essential, not optional.

These stats describe 2,836 vehicles as a group. The specific vehicle you're looking at could be the one good example or the one outlier. Run its registration to find out.

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See this vehicle's full MOT history & AI hunches

Spot recurring advisories, hidden issues, and how it compares to 2,836 BMW 420i M Sport Auto cars.

Before you buy a 2021 BMW 420i M Sport Auto

Based on MOT data from 2,836 vehicles — here's what to check.

📋 Check the full MOT history. 12.3% of these vehicles have had a dangerous defect recorded - recurring advisories often signal problems years before they become failures.
Search the reg on CarHunch for the full MOT history, reliability stats and a free AI-powered analysis of that exact vehicle.
🔍 Brake pipes, sills and subframes are the key areas on a vehicle this age — structural rust is hard to spot without getting underneath. A mechanic will check all of this before you commit, and give you a concrete basis to negotiate on price. Inspection →
📄 Outstanding finance, insurance write-offs and clocking won't appear in the MOT records — a dedicated history check covers all of this. Our link gets you 20% off automatically. History Get 20% off via CarHunch

Pass Rate by Fuel Type

Fuel type	Vehicles	Pass rate	Avg failures
Petrol (97%)	2,753	92.4%	0.24
Other (3%)	83	98.8%	0.02

Colour Breakdown

Based on 13,555 BMW 420i M Sport Auto vehicles registered in the UK — across all years. From DVLA registration records.

Black 24.2%

3,278

Grey 24%

3,247

Blue 23.4%

3,171

White 16.5%

2,234

Green 9.1%

1,236

Red 2.1%

285

Orange 0.7%

Silver 0%

Purple 0%

Mileage Distribution

Most 2021 BMW 420i M Sport Auto vehicles sit in the blue band. If the vehicle you're looking at is outside it, it's either unusually low or high mileage for its age.

25,466

typical

18,346

low mileage

34,287

high mileage

Half of all 2021 BMW 420i M Sport Auto vehicles fall between 18,346 and 34,287 miles.

Is the mileage you're seeing normal?

✓ Under 18,346 miles — lower than most. Could be great, or could be a vehicle that rarely moved. Check test frequency and mileage progression in the MOT history.

✓ 18,346–34,287 miles — normal for age. This is where most 2021 BMW 420i M Sport Autos sit.

⚠ Over 46,287 miles — higher than typical. Not necessarily a problem, but check service history and look out for advisory build-up on tyres and brakes.

2021 BMW 420i M Sport Auto — Still on the Road

Almost all 2021 BMW 420i M Sport Autos are still on the road.

Strong survival — 2,672 vehicles still getting MOTs in 2025, 100% of the peak.

Based on vehicles from this manufacture year that had at least one MOT test in each calendar year. Data from 2023–2025.

MOT History Averages

2.3

Avg MOT tests per vehicle

0.23

Avg failures per vehicle

Avg advisories per vehicle

Other model years — BMW 420i M Sport Auto: All 420i M Sport Auto years → Which year to buy? →

2020 2022 2023 2024 2025

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Compare with another model

See how the 2021 BMW 420i M Sport Auto stacks up against a rival.

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