Should I check the MOT history before buying a 2021 Mercedes Benz B?

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 Mercedes Benz B?

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 Mercedes Benz B?

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 Mercedes Benz B reliable?

Based on MOT data from 1,220 vehicles, the 2021 Mercedes Benz B has a first-time MOT pass rate of 94.5%, indicating generally reliable for its class. Always check the full MOT history of any specific vehicle before buying.

What are common problems with the 2021 Mercedes Benz B?

The most frequently recorded MOT issues on the 2021 Mercedes Benz B are: Nearside Front Tyre worn close to legal limit/worn on edge (25.2% of vehicles), Offside Front Tyre worn close to legal limit/worn on edge (25.1% of vehicles), Nearside Rear Tyre slightly damaged/cracking or perishing (13.8% of vehicles). These figures are based on actual MOT test records — search a specific registration on CarHunch to see its individual history.

Do I need an HPI check when buying a 2021 Mercedes Benz B?

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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Mercedes Benz B (2021)

1,220 real MOT outcomes analysed • 94.5% first-time pass rate

2021 Mercedes Benz B

CarHunch analysed 1,220 real MOT records for the 2021 Mercedes Benz B. 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 Common Issues 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 Mercedes-Benz B is notably reliable, with a 94.5% first-time pass rate that significantly outpaces the UK average of 80%—and this consistency holds equally across both petrol and diesel variants. Only 4.8% of vehicles have ever recorded a dangerous defect, which is well below concerning levels.

These cars are running at sensible mileage for their age, averaging 23,832 miles, and they generate very few failures (0.18 per vehicle) when they do come in for MOT. The modest advisory count of 1.1 per vehicle suggests routine wear rather than systemic issues, so a buyer inspecting one should focus on service history and accident damage rather than worrying about mechanical surprises.

The 2021 Mercedes Benz B passes its MOT first time more often than most UK vehicles (94.5% vs ~80% average) — and when it does fail, it's usually something minor and cheap to fix.

First-time pass

94.5%

UK average ~80%

Better than average

Dangerous (ever)

4.8%

At least once in MOT history

Check this vehicle

Avg failures / car

0.18

Over 2.4 tests on record

Low

Typical mileage

20k

Middle half: 14k–29k

For context

✅ Good baseline reliability. A 94.5% first-time pass rate puts this well above the UK average — it's a well-sorted vehicle in this age bracket.

These stats describe 1,220 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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What tends to go wrong

Across 1,220 vehicles — figures show how many had each issue flagged at least once in their MOT history.

Tyre wear 25.2%

Nearside Front Tyre worn close to legal limit/worn on edge · Offside Front Tyre worn close to legal limit/worn on edge · Nearside Rear Tyre slightly damaged/cracking or perishing · …

Budget for a full set — on a vehicle this age, tyres are expected consumables. An inspection will confirm how much is left.

Brake wear 8.5%

Rear Brake pad(s) wearing thin · Front Brake pad(s) wearing thin · Front Brake disc worn, but not excessively

Ask the seller when brakes were last serviced. If they don't know, factor in the cost.

Other issues 5.3%

Nearside Rear Child Seat fitted not allowing full inspection of adult belt · Windscreen damaged but not adversely affecting driver's view

Lighting 3.2%

Supplementary restraint system warning lamp indicates a fault

Usually cheap to fix. Worth confirming all lights work before collecting.

Data covers a 3-year window centred on 2021.

See this vehicle's full MOT history & AI hunches

Spot recurring advisories, hidden issues, and how it compares to 1,220 Mercedes Benz B cars.

Before you buy a 2021 Mercedes Benz B

Based on MOT data from 1,220 vehicles — here's what to check.

📋 Check the full MOT history. 4.8% 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 (60%)	738	94.5%	0.18
Diesel (40%)	482	94.5%	0.17

Colour Breakdown

Based on 7,843 Mercedes Benz B vehicles registered in the UK — across all years. From DVLA registration records.

Grey 28.2%

2,214

Black 19.6%

1,541

Blue 16.2%

1,268

White 15%

1,179

Silver 14.5%

1,138

Red 6.4%

503

Mileage Distribution

Most 2021 Mercedes Benz B 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.

19,794

typical

13,503

low mileage

28,625

high mileage

Half of all 2021 Mercedes Benz B vehicles fall between 13,503 and 28,625 miles.

Is the mileage you're seeing normal?

✓ Under 13,503 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.

✓ 13,503–28,625 miles — normal for age. This is where most 2021 Mercedes Benz Bs sit.

⚠ Over 38,643 miles — higher than typical. Not necessarily a problem, but check service history and look out for advisory build-up on tyres and brakes.

2021 Mercedes Benz B — Still on the Road

Almost all 2021 Mercedes Benz Bs are still on the road.

Strong survival — 1,204 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

2.4

Avg MOT tests per vehicle

0.18

Avg failures per vehicle

1.1

Avg advisories per vehicle

Other model years — Mercedes Benz B: All B years → Which year to buy? →

2019 2020 2022

Or browse all models: Mercedes Benz →

Compare with another model

See how the 2021 Mercedes Benz B stacks up against a rival.

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