The new variant of the popular executive car will be offered in both the saloon and Touring estate forms and will benefit from the input of the firm’s M performance division.
The M340d will use a 3.0-litre six-cylinder diesel engine with a 48V starter-generator that can add an extra 11bhp. As well as offering 335bhp, the mild-hybrid powertrain produces a maximum of 516lb ft of torque. This compares to the 369bhp and 369lb ft of the six-cylinder petrol M340i.
BMW says the M340d can achieve a 0-62mph time of 4.6sec in saloon form and 4.8sec as an estate.
Power is delivered to all four wheels as needed through an eight-speed automatic gearbox. The 340d will also offer specially tuned M Sport suspension, brakes and differential as standard, along with a number of exterior design tweaks to aid aerodynamics.
The mild-hybrid technology also allows for engine-off coasting, and BMW says it allows the diesel powertrain to operate in its most efficient load range as much as possible, boosting fuel consumption and efficiency.
The model is claimed to achieve between 49 and 53mpg, with CO2 emissions ranging from 139-149g/km for the saloon and 143-153g/km for the estate.
The new range-topping diesel model is part of an expanding 3 Series range that BMW will showcase at Geneva, including a new four-wheel-drive 330e Touring.