BMW will launch an updated version of its 3-Series saloon and touring in September, with subtle visual changes and improved efficiency for most diesel models.

The revised 330d features a new all-aluminium common rail diesel engine producing 245bhp and 384lbs/ft torque, up 14bhp and 15lbs/ft compared to its predecessor, but with better fuel economy and emissions.

As a result, the two thirds of buyers who opt for an automatic will pay the same VED as those who buy a manual, with all 330d models now falling into band D.

Similar benefits are offered for the revised 325d and 335d, now more efficient than before and with no tax penalty for losing the clutch pedal.

From September, saloon and touring variants of the 318d will be available with an automatic gearbox for the first time, recording a combined fuel consumption figure of 52.3mpg and emitting 144g/km CO2, compared to 60.1mpg and 123g/km for the manual.

Petrol units will remain unchanged following the introduction of Efficient Dynamics across the range last year.

Exterior changes are subtle, with new alloy wheels and minor tweaks to exterior panels to bring the design up to date, while all models will be fitted with twin corona side lights as standard.

Inside, the 3-Series gains active head restraints, a more advanced iDrive system and redesigned dash, featuring new materials aimed at giving a more luxurious feel.

The new 3-Series saloon and touring go on sale on September 20, and pricing will be announced closer to the launch.