Family hatchback · 2005–2021 cars

Mercedes-Benz B-Class reliability

The Mercedes-Benz B-Class fails 26.5% of first MOT tests, 5% fewer MOT fails than the average car its age and mileage, based on 243,079 DVSA MOT tests from 2022 to 2024.

About averageReliability score 55/100#24 of 65 family hatchbacks

Checking a Mercedes-Benz B-Class before you buy?

first-time MOT fail rate (all cars: 28.4%): 26.5%; first-time MOT fail rate (all cars: 28.4%)
fails than cars of the same age and mileage: 5% fewer; fails than cars of the same age and mileage
MOT tests analysed, 2022 to 2024: 243,079; MOT tests analysed, 2022 to 2024
typical miles a year, from MOT readings: 7,000; typical miles a year, from MOT readings

What this means for buyers

The B-Class has 5% fewer MOT fails than cars of the same age and mileage. Its first-time fail rate is 26.5%, against 28.4% for all cars, and it ranks 24 of 65 family hatchback models. Cars from 2020 did best, with 34% fewer MOT fails than comparable cars, while 2011 cars had 11% more. Seat belts and airbags are the weak spot, with 66% more fails than comparable cars.

A good record is no reason to skip checks. Ask for the full MOT history and look for repeat faults. Then check the car for the most common failures: a coil spring that's fractured or broken (2.97% of tests), a CV joint boot that's split or insecure (1.78%), a worn suspension ball joint (1.58%) and tyres cut to the ply or cords (1.52%). Make sure every seat belt works and the airbag warning light goes out after start-up.

MOT fail rate by age

How the Mercedes-Benz B-Class ages

Each point is the share of Mercedes-Benz B-Classs of that age that failed their MOT first time, against all cars of the same age.

Mercedes-Benz B-ClassAll cars

Mercedes-Benz B-Class first-time MOT fail rate by age
Age at MOT (years)	Mercedes-Benz B-Class	All cars
3	9%	12.3%
4	11%	14.1%
5	12.8%	16.4%
6	15.8%	19.1%
7	17.9%	22.1%
8	21.2%	25.5%
9	23.8%	28.8%
10	27.5%	31.8%
11	31%	34.6%
12	36%	37.3%
13	40.8%	39.5%
14	42.9%	41.1%
15	43.2%	42.3%
16	44.5%	42.9%
17	43.4%	43.4%
18	45%	43.5%

By year

The best and worst Mercedes-Benz B-Class years

2020 cars come out best and 2011 cars worst, once age and mileage are taken into account.

Mercedes-Benz B-Class MOT results by year of first registration
First registered	Tests	Fail rate	Against same-age cars	Typical mileage
2021	761	4.9%	55% fewer fails	21,977
2020 B-Class	5,538	7.4%	34% fewer fails	22,559
2019 B-Class	12,153	9.8%	18% fewer fails	23,882
2018 B-Class	13,837	12.4%	9% fewer fails	29,042
2017 B-Class	19,902	14.9%	10% fewer fails	38,520
2016 B-Class	18,862	16.8%	13% fewer fails	45,085
2015 B-Class	19,696	19.4%	15% fewer fails	54,073
2014 B-Class	29,108	23.2%	13% fewer fails	62,905
2013 B-Class	24,739	25.1%	15% fewer fails	68,946
2012 B-Class	20,456	27.9%	14% fewer fails	75,798
2011 B-Class	12,470	38.8%	11% more fails	76,595
2010 B-Class	16,163	39.5%	6% more fails	82,425
2009 B-Class	15,659	40.9%	3% more fails	89,144
2008 B-Class	13,105	43.6%	5% more fails	95,020
2007 B-Class	10,440	43.6%	3% more fails	98,117
2006 B-Class	8,412	44%	2% more fails	98,591
2005 B-Class	1,778	43.4%	1% fewer fails	100,892

Common problems

What fails most on a Mercedes-Benz B-Class

Its weak spot is seat belts and airbags: 66% more fails there than cars of the same age and mileage.

Fail rate by area

Lights and electrics9.9%9% below avg
Suspension8.1%9% below avg
Tyres6.7%8% above avg
Brakes6.1%3% below avg
Windscreen, wipers and mirrors3.9%14% below avg
Body, chassis and structure3%4% below avg
Exhaust, emissions and leaks2.9%2% above avg
Seat belts and airbags1.4%66% above avg
Wheels0.7%106% above avg

Average for cars of the same age and mileage

Top MOT failures

1
Coil spring fractured or broken 2.97% of tests
A broken coil spring can leave the car sitting low or unstable, so it must be replaced before driving.
2
CV joint boot split or insecure 1.78% of tests
A split CV boot lets dirt in and grease out, so the joint wears and may need full replacement.
3
Suspension ball joint excessively worn 1.58% of tests
A worn ball joint can fail and cause loss of steering control, so it must be replaced promptly.
4
Tyre cut reaching ply or cords 1.52% of tests
A cut reaching the ply or cords weakens the tyre and can cause a burst, so it must be replaced.
5
Registration plate lamp not working 1.52% of tests
A dark number plate lamp makes the plate hard to read at night, which is illegal and must be fixed.
6
Brake pads worn below 1.5mm 1.5% of tests
Pads worn below 1.5mm lose stopping power and can damage discs, so replacement is needed before the car is driven.
7
Anti-roll bar linkage dust cover unsealed 1.45% of tests
A damaged dust cover lets dirt into the linkage joint, speeding wear and possibly needing a future repair.
8
Tyre ply or cords exposed 1.38% of tests
Exposed ply or cords can let the tyre fail suddenly, so the tyre must be replaced before the car is driven.

Most common advisories

Not a fail yet, but worth pricing in: these show up on a Mercedes-Benz B-Class's MOT certificate most often.

Tyre worn close to legal limit12.03%
Tyre slightly damaged or cracking8.39%
Brake disc pitted or scored6.77%
Brake pads wearing thin6.55%
Brake pipes corroded and greasy6.53%
Brake discs showing some wear2.76%

Before you buy

What to check on a used Mercedes-Benz B-Class

1
Coil spring fractured or broken
A broken coil spring can leave the car sitting low or unstable, so it must be replaced before driving.
2
CV joint boot split or insecure
A split CV boot lets dirt in and grease out, so the joint wears and may need full replacement.
3
Suspension ball joint excessively worn
A worn ball joint can fail and cause loss of steering control, so it must be replaced promptly.
4
Tyre cut reaching ply or cords
A cut reaching the ply or cords weakens the tyre and can cause a burst, so it must be replaced.
5
Every MOT since new
Look for the faults above coming back year after year: it shows how the car has been looked after.
6
The mileage record
A typical Mercedes-Benz B-Class covers about 7,000 miles a year. A big gap or a drop between MOTs is a warning sign.
7
Finance, stolen and write-off
The records the MOT can't show. A Full Check (£9.99) covers all three before you hand over any money.

Fuel types tested

Diesel66.5%
Petrol32.8%
Electric0.6%
Hybrid0.1%
LPG0%

Most common colours

Black, Silver, Grey, Blue, White

Average engine size: 1.7 litres.

Compare

How the Mercedes-Benz B-Class compares with its rivals

Mercedes-Benz B-Class against similar models
Model	Fail rate	Against same-age cars
Mercedes-Benz CLA	17.7%	14% fewer MOT fails than the average car its age
Volkswagen Scirocco	28.5%	10% fewer MOT fails than the average car its age
Toyota Corolla	32.2%	9% fewer MOT fails than the average car its age
Mercedes-Benz B-Class	26.5%	5% fewer MOT fails than the average car its age
Mazda 3	31.9%	8% more MOT fails than the average car its age
Volvo V40	25.9%	10% more MOT fails than the average car its age
Hyundai i30	34%	20% more MOT fails than the average car its age

Every family hatchback ranked in the family hatchback reliability index, or all Mercedes-Benz models.

Questions

Mercedes-Benz B-Class questions, answered

Is the Mercedes-Benz B-Class reliable?

On MOT results, the Mercedes-Benz B-Class is about average: it fails 26.5% of first MOT tests, 5% fewer MOT fails than the average car its age and mileage. It ranks 24 of 65 family hatchback models in our index.

What fails most on a Mercedes-Benz B-Class MOT?

The most common MOT failures on the Mercedes-Benz B-Class are coil spring fractured or broken (2.97% of tests), cv joint boot split or insecure (1.78% of tests), suspension ball joint excessively worn (1.58% of tests). By area, lights and electrics fails 9.9% of its tests.

Which Mercedes-Benz B-Class year is the most reliable?

Among years with 1,000+ tests, 2020 cars do best (34% fewer MOT fails than the average car its age) and 2011 cars do worst (11% more MOT fails than the average car its age).

How many miles does a Mercedes-Benz B-Class do a year?

A typical Mercedes-Benz B-Class covers about 7,000 miles a year, from the mileage recorded at its MOTs. Check the car you're looking at against that with a free mileage check.

How do I check a Mercedes-Benz B-Class before I buy it?

Enter its registration for a free check of its MOT history, mileage, ULEZ status and tax. Before you pay, a Full Check (£9.99) shows outstanding finance, stolen and write-off records.

Source: DVSA anonymised MOT test results, 2022 to 2024, class 4 vehicles aged 3 to 25, normal tests only. How we compare like with like: our methodology.

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