The new BMW 4 Series Convertible has been revealed, ditching the previous-generation model’s folding hardtop arrangement in favour of a fabric roof (but inheriting the coupé’s controversial grille).

Described by the Munich-based firm as a “panel bow softtop”, BMW says the new roof construction combines the “strengths of a retractable hardtop and the puristic appeal of a fabric roof”. It comprises large panel bow elements with a flush-fitting glass rear window, “several” layers of insulation and a fabric cover available in black as standard and anthracite silver effect as an option.

BMW claims the “acoustic and thermal comfort” of this new softtop roof is “far superior” to that of a conventional softtop, while weighing 40 percent less than the outgoing model’s retractable hardtop.

The roof is powered by an electric motor that enables it to open or close in 18 seconds, including at speeds up to 50 km/h. The softtop compartment, meanwhile, allows luggage capacity to be increased from a claimed 300 to 385 litres when the roof is closed.

Measuring 4 768 mm from nose to tail, the new topless four-seater model is some 128 mm longer than its predecessor, while width has increased by 27 mm to 1 852 mm. The wheelbase is up 41 mm to 2 851 mm, while the track widths have been increased 28 mm at the front and 18 mm at the rear.

BMW says it has added convertible-specific bracing, an aluminium shear panel at the bottom of the front end and side skirts with “extremely high torsional rigidity”. The open-top model furthermore gains model-specific tweaks to the chassis geometry, mounting and set-up.

What’s happening under the bonnet? Well, the biggest news is the arrival of an M440i xDrive variant, which employs a turbocharged 3,0-litre straight-six sending 275 kW and 500 N.m to all four corners via an eight-speed automatic transmission (the latter gearbox standard across the line-up). BMW says that’s enough for a sprint from zero to 100 km/h in 4,9 seconds, a full four-tenths slower than the coupé with the same powertrain.

There will also be two turbocharged 2,0-litre, four-cylinder petrol units (with the 420i offering 135 kW and the 430i some 190 kW) and a 2,0-litre, four-cylinder turbodiesel in the form of the 140 kW 420d. A pair of straight-six turbodiesel engines are also on the cards.

Inside, the new 4 Series Convertible borrows much from its coupé sibling, though adds items such as automatically extending and retracting sealbelt feeders up front. Model-specific options, meanwhile, include a wind deflector and neck warmers integrated into the front head restraints.