BMW is going large with its 8 Series range with the introduction of a four-door Gran Coupe.

Significantly longer than the standard coupe the bigger version also comes with a larger boot and more room in the rear.

It will be available in September and priced from £69,340 is cheaper than the coupe and cabriolet models.

That version will be powered by a new straight six petrol engine developing 340hp which gives the 8 Series Gran Coupe a 0 to 60 time of 5.2 seconds, a restricted top speed of 155mph and an official fuel return of 38.2mpg at best. Emissions are 168g/km.

The 840i Gran Coupe will be joined by a 320hp six cylinder diesel powered 840d with xDrive all-wheel-drive which is almost as quick at 5.1 seconds 0 to 60 but with the benefit of 45.6mpg and lower emissions of 162g/km.

The diesel is priced from £73,915 while the range topping M850i xDrive is priced from £97,720 and has a V8 petrol engine which develops 530hp.

As such, BMW says it is good for 0 to 60 acceleration in 3.9 seconds with fuel figures of 28.5mpg and emissions of 229g/km.

The Gran Coupe has grown by some 201mm over the standard 8 Series coupe and measures 5.082 metres in length. It is also 30mm wider and 61mm higher while the rear track at 1.671 metres is the widest of any current BMW.

The wheelbase is also extended by 201mm to 3.023 metres which helps create the extra space inside and boot space is 440 litres. The rear seats fold for more room if needed.

Equipment levels are similar to those of the other 8 Series models which see the Gran Coupe come with adaptive LED headlights as standard, adaptive suspension and active steering. A panoramic sunroof is an option.

All versions have eight-speed automatic gearboxes and the M850i xDrive Gran Coupe has an additional front spoiler to help reduce lift at high speed.

An extended centre console stretches into the back of the Gran Coupe and BMW describes the new model as a 4+1 seater with a middle rear seat that is suitable only for short journeys.

The car will have its world premiere in Munich next week.