We drive early version of BMW’S top-spec 8 Series

● FIRST DRIVE Verdict on prototype M850i in Wales

THE new BMW 8 Series arrives next month to replace the 6 Series, but we’ve joined the development team in Wales to try the 523bhp M850i xdrive just before its specification is finalised.

The range-topper at launch gets a 4.4-litre twin-turbo V8, hooked up to an eight-speed auto gearbox. BMW’S xdrive AWD is standard, along with rearwheel steering, an electronic rear e-diff, electronic damping and 20-inch wheels.

While engineers had disguised most of the cabin, we were allowed to see the instrument pack; the digital display is bracketed by an angular speedo and will be shared with the forthcoming X5 SUV.

The big coupé’s V8 starts with an offbeat rumble, but fades as soon as we’re moving. The steering feels a little light initially, but gains weight at higher speeds, by which point the adaptive damping is doing a brilliant job of smoothing out lumpy Welsh asphalt.

Through sweeping curves and tighter corners, the M850i remains poised in a natural way. Unleashing the torque of the twin-turbo V8 can’t disturb the car’s ride and composure, although you sense the circa-1,900kg mass now and then.

In the Sport setting, the transmission holds the gears for best performance and the engine finds its voice, including some pops and bangs. The chassis absorbs the impact of a lot of the road surface, but the steering lacks that same connected feel and tactility; it’s one element that seems as if it could still be improved.

The M850i is clearly fast and capable, but it’s more a talented GT than a fullblown sports coupé. That’ll be the job of the M8, which is also coming, along with a convertible and four-door Gran Coupé.