Both engines come mated to a standard eight-speed torque converter-equipped, ZF-produced automatic gearbox and BMW’s four-wheel drive xDrive system. The M850i xDrive convertible also receives an electronically controlled rear differential lock – a feature available as an option on the 840d xDrive convertible.
The 1955kg 840d xDrive can crack 0-62mph in 5.2sec, the 2055kg M850i xDrive in 3.9sec, and both have a limited top speed of 155mph. Later next year, the M8 will join the range using an even more potent twin-turbocharged version of the M850i’s 4.4-litre V8. An 840i is also set to be introduced as an entry-level version.
Predictably, the new 8-series convertible mirrors the look of the new 8-series coupé, with a bold front end and muscular lines. Its multi-layer fabric roof, which comes in a choice of either a standard black or optional anthracite colour, opens in 15sec at the touch of a button at speeds up to 31mph, automatically stowing beneath a tonneau cover trimmed with the same slush moulded plastic as the dashboard and door trims at the rear of the two-plus-two cabin. BMW claims 350-litres of boot capacity with the roof in place, but reduced when it is stowed. To accommodate lengthy items, the rear seats split and fold in 50:50 form to free up greater load space.
A plastic wind deflector similar to that already seen on 6-series convertibles can be erected to reduce wind buffeting when the roof is down, although it requires the rear seats of the 8-series convertible to be unoccupied.
Despite its higher positioning, the new 8-series convertible is 54mm shorter than the old 6-series convertible at 4843mm in length, while its width and height is put at 1902mm and 1339mm respectively. It also uses the same wheelbase as the recently introduced 8-series coupé at 2822mm.