BMW will add a third model to its newly established 4-series line-up with the launch of a four-door Gran Coupé.

Set to make its world debut at the Geneva motor show, the new liftback model will join the 4-series coupé and convertible models as “a visually racier but eminently practical four-door alternative to the traditional 3-series saloon”.

The 4-series Gran Coupé uses the same structure as the 4-series coupé and 3-series saloon, with a 2810mm wheelbase. The four-door layout has been made possible by shortening the length of the front doors to accommodate smaller rear doors. All doors are frameless and the B-pillars have been beefed up for added structural rigidity.

At 4640mm in length, 1825mm in width and 1370mm in height, the 4-series Gran Coupé is exactly the same length and width but slightly taller than the 4-series coupé. The additional strengthening and rear doors are claimed to add 100kg to the kerb weight.

Helping to differentiate the new car visually is a more heavily curved roofline than the 4-series coupé’s. The 4-series Gran Coupé also adopts a more heavily raked windscreen and rear window than the 3-series saloon. Its boot capacity is put at 480 litres, the same as a 3-series saloon’s.

The 4-series Gran Coupé will have the same line-up of four and six-cylinder engines as the 4-series coupé. Rear drive will be standard, with all-wheel drive optional on some models.

Prices are set to start at about £5000 higher than an equivalent 3-series saloon. UK sales will start in June.