Mercedes-Benz B-Class running costs and reliability

2019 onwards (change model)

Running costs rating: 3.6 out of 53.6

Written by Keith Adams Updated: 22 August 2024

Miles per pound (mpp) ⓘ

Low figures relate to the least economical version; high to the most economical. Based on WLTP combined fuel economy for versions of this car made since September 2017 only, and typical current fuel or electricity costs.

Petrol engines	5.1 - 6.9 mpp
Diesel engines	6.6 - 7.9 mpp
Plug-in hybrid petrol engines *	6.0 - 6.4 mpp

* Fuel economy of the engine when operating without assistance from the electric motor and battery.

What is miles per pound?

Fuel economy ⓘ

Low figures relate to the least economical version; high to the most economical. Based on WLTP combined fuel economy for versions of this car made since September 2017 only.

Petrol engines	34.5 - 47.1 mpg
Diesel engines	51.4 - 61.4 mpg
Plug-in hybrid petrol engines *	40.9 - 43.5 mpg

* Fuel economy of the engine when operating without assistance from the electric motor and battery.

View mpg & specs for any version

What are the running costs?

Diesel the more frugal option
No plug-in hybrid
Mild hybrid economy boost not huge

On paper the B-Class isn’t as efficient as the BMW 2 Series Active Tourer, but it’s not far off. Officially, the petrol should do mid-40s mpg with the diesel better at mid-50s. When driven with restraint on motorways and A roads, we were able to get close to the claims in the diesel, with 52mpg achievable, while harder driving had us returning mpg in the 40s.

Diesel models get a regular stop/start system while the petrol is a mild hybrid. This allows the engine to be turned off for extended periods of time even when the car is moving. It does save a little fuel, but the petrol will still be a thirstier option. That means any B-Class you choose will get you between 5.1 - 7.9 mpp (miles per pound).

Servicing and warranty

Servicing intervals for the B-Class are every 12 months or 15,500 miles – whichever comes sooner. A range of service packs are available, and can be passed on if the vehicle is sold to a new owner.

Every new B-Class comes with a comprehensive three-year, unlimited mileage warranty from the manufacturer, along with three years’ roadside assistance. Compared with up to 10 years offered by rivals, Mercedes-Benz’s warranty is beginning to look off-the pace.

Reliability

Few reported reliability issues, but fewer owners
No recalls listed for pre-facelift models
Plenty of advanced kit, which could eventually be costly to fix

The overall quality and reliability of the B-Class seem to be have been a bit of an issue. The old B-Class’s reliability record wasn’t good – but at least our Mercedes-Benz B-Class owner’s reviews haven’t reported any major problems, mainly because there aren’t many owners to deliver any A-Class-style negative feedback.

It will be worth keeping an eye on the fancy interior as time goes on, however, as the array of high-tech components offering plenty of potential for things to go wrong, and we hear that trim durability isn’t as good as it should be. We’ll keep monitoring the situation.