BMW is improving fuel economy and emissions across its range by introducing mild-hybrid powertrains to a number of its models.

The German firm says that from spring 2020, the battery-assistance technology will be fitted as standard to all iterations of the 320d, as well as xDrive20d versions of the X3 and X4.

The powertrains feature a starter generator with an additional battery to power it, which can take over running the car, particularly when slowing or stopping, so the engine can be turned off to reduce fuel.

This system also provides up to 11bhp of extra performance when accelerating, while the ‘coasting’ function has been optimised to improve economy.

BMW is overhauling its powertrain options ahead of strict emissions targets coming in for 2021, claiming that 40 of its models will meet Euro 6d targets this year.

Other updates to the range include new engine options for the 1 Series and 3 Series to increase the variety on offer, as well as additional equipment for the 7 Series, 8 Series, X5, X6 and X7.