Mercedes-Benz B-Class: MOT pass rate and reliability data

The Mercedes-Benz B-Class fails its first MOT more often than the average UK car, by 2 percentage points. These figures come from the DVSA's full year of anonymised MOT results, covering 63,986 individual Mercedes-Benz B-Class tests. Nothing here is an estimate or a survey.

The numbers

What this means if you are buying one

A 74.7% first-time pass rate means roughly 25 in every 100 Mercedes-Benz B-Class presented for MOT fail on the first attempt. That is worse than average, so budget for remedial work and treat a fresh 12-month MOT as a genuine selling point rather than a given. The average Mercedes-Benz B-Class tested had covered 73,962 miles and was built around 2013.

What this means at salvage auction

Pass rate is a proxy for what a car costs to keep on the road. On a Mercedes-Benz B-Class bought as a repairable salvage, assume the mechanical side needs more than the visible accident damage, and pad your repair estimate accordingly.

Before you bid: run the lot through the analyzer, check the car's own record, check the mileage, decode the VIN, and if it carries a marker use the write-off value calculator. Or compare it against another model.

Looking at a specific Mercedes-Benz B-Class rather than the model in general? The free check covers its MOT and mileage history, and the full HPI report confirms the insurance write-off category, outstanding finance and whether it is recorded stolen, from licensed data for 5 credits. Already own one that has been damaged? Work out whether fixing it beats selling it with the repair or scrap calculator, and see what damaged Mercedes-Benz B-Class actually sold for at UK salvage auction.

Most common MOT failures on a Mercedes-Benz B-Class

1. A direction indicator lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning, 1.3% of tests (2.73x the national rate for this defect)
2. A suspension joint dust cover missing or no longer prevents the ingress of dirt etc, 3.6% of tests (2.7x the national rate for this defect)
3. A rear registration plate lamp or light source missing or inoperative in the case of a single lamp or all lamps, 1.6% of tests (2.54x the national rate for this defect)
4. Lamp emitted colour, position or intensity not in accordance with the requirements, 0.9% of tests (2.13x the national rate for this defect)
5. Brake pipe damaged or excessively corroded, 1.7% of tests (2.09x the national rate for this defect)
6. A transmission shaft constant velocity joint boot missing or no longer prevents the ingress of dirt etc, 2.2% of tests (1.94x the national rate for this defect)
7. A spring or spring component fractured or seriously weakened, 3.1% of tests (1.88x the national rate for this defect)
8. Engine MIL illuminated indicating a malfunction, 1.6% of tests (1.72x the national rate for this defect)
9. A tyre seriously damaged, 3.1% of tests (1.55x the national rate for this defect)
10. Windscreen washers not working or not providing sufficient fluid to clear the windscreen, 1.8% of tests (1.42x the national rate for this defect)

From 95,936 DVSA-tracked Mercedes-Benz B-Class tests, 2024. DVSA testers marked 5.42% of these flagged Mercedes-Benz B-Class defects as "dangerous", meaning the tester judged the car unsafe to drive away, against 4.97% nationally.

Mercedes-Benz B-Class pass rate by model year

Pass rates fall steadily as cars age, so the model year matters as much as the model. First-time pass rate for each Mercedes-Benz B-Class year:

• 2005 Mercedes-Benz B-Class - 65.6% first-time pass, 407 tests
• 2006 Mercedes-Benz B-Class - 63.5% first-time pass, 2,057 tests
• 2007 Mercedes-Benz B-Class - 63.7% first-time pass, 2,696 tests
• 2008 Mercedes-Benz B-Class - 61.9% first-time pass, 3,513 tests
• 2009 Mercedes-Benz B-Class - 64.3% first-time pass, 4,328 tests
• 2010 Mercedes-Benz B-Class - 65.2% first-time pass, 4,581 tests
• 2011 Mercedes-Benz B-Class - 65.1% first-time pass, 3,587 tests
• 2012 Mercedes-Benz B-Class - 74.6% first-time pass, 5,795 tests
• 2013 Mercedes-Benz B-Class - 76% first-time pass, 7,124 tests
• 2014 Mercedes-Benz B-Class - 78.4% first-time pass, 8,265 tests
• 2015 Mercedes-Benz B-Class - 82.1% first-time pass, 5,653 tests
• 2016 Mercedes-Benz B-Class - 83.7% first-time pass, 5,374 tests
• 2017 Mercedes-Benz B-Class - 85.7% first-time pass, 5,715 tests
• 2018 Mercedes-Benz B-Class - 87.9% first-time pass, 3,919 tests
• 2019 Mercedes-Benz B-Class - 91.5% first-time pass, 585 tests

Mercedes-Benz B-Class by fuel type

Diesel and petrol versions of the same car fail on different things, so the fuel type moves the number:

• Diesel Mercedes-Benz B-Class - 75.1% first-time pass, 43,228 tests
• Petrol Mercedes-Benz B-Class - 75.2% first-time pass, 19,996 tests
• Electric Mercedes-Benz B-Class - 84.5% first-time pass, 399 tests

Other Mercedes-Benz models

• Mercedes-Benz C - 77.4%
• Mercedes-Benz A-Class - 78.7%
• Mercedes-Benz E - 79.2%
• Mercedes-Benz A - 89.5%
• Mercedes-Benz Vito - 72.7%
• Mercedes-Benz Gla - 85.2%
• Mercedes-Benz Glc - 87.8%
• Mercedes-Benz Cla - 82.8%

Models with a similar pass rate

• Smart (Mcc) Roadster - 74.8%
• Volkswagen Passat - 74.7%
• Peugeot 3008 - 74.7%
• Porsche 924 - 74.7%
• Vauxhall Adam - 74.6%
• DS Ds3 - 74.6%

If this car is a salvage or write-off

• What does Cat N mean? Category N explained
• What does Cat S mean? Category S explained
• Cat S vs Cat N: the real differences

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All 2,005 models ranked by MOT pass rate