BMW's stylish 6 Series range is being expanded to three models next month with the arrival of the Gran Coupe.

And the German prestige manufacturer is promising its first four-door coupe will combine the sporty appeal of a classic grand tourer with the space of an executive saloon.

A new 450bhp V8 unit heads a range of three TwinPower Turbo engines, which also includes six-cylinder petrol and six-cylinder diesel powerplants.

All three engines drive through an eight-speed automatic transmission and come with the full suite of EfficientDynamics technologies, including Auto Start-Stop for lower fuel consumption and emissions.

Aluminium has been extensively used in the body and chassis to reduce weight, ensuring that both the £61,390 640i and £63,900 640d models can blast from 0-62 in 5.4 seconds and on to an electronically limited top speed of 155mph.

Economy for the diesel is a Combined 49.6mpg with CO2 emissions of 148g/km while the petrol model can return 35.8mpg with emissions of 181g/km.

Topping the trio is the 650i Gran Coupe at £70,650 and capable of 0-62 in 4.6 seconds. Its fuel figure is 31.7mpg with emissions of 206g/km.