We’re yet to drive the M850i or 840d Gran Coupé, but we've tried both engines in the two-door 8 Series Coupé. It’s reasonable to assume that the M850i will prove highly responsive, muscular and extremely rapid (0-62mph officially takes just 3.9sec). Meanwhile, the 840d should impress with effortless shove from the get-go, making overtaking a breeze.
We have driven the 840i; it sounds quite throaty and pulls consistently throughout its rev range. However, being a petrol, you have to work it relatively hard to maximise its performance; the 840d should deliver more effortless pace. But then, in a sporty car, revving the engine is all part of the fun, and while a Porsche Panamera 4S is quicker, the 840i will dispatch the 0-62mph dash in a highly respectable 5.2sec. Its eight-speed automatic gearbox is quick, smooth and very adept at picking the right gear for any given situation.
The Gran Coupé isn’t quite as agile as the 8 Series Coupé on which it’s based, or as the Panamera 4S; it’s softer than they are and leans a little more through turns. It feels beautifully balanced on twisty roads, though, and is more fun than an Audi A7 Sportback. In the dry, the 840i appears uncompromised by its lack of four-wheel drive (other versions come with four-wheel drive, as do most of its rivals); there’s plenty of traction off the line and it exhibits strong cornering grip.
The steering is sweeter than the A7 Sportback’s, if not quite as direct as the Panamera’s. It’s light (although you can ramp up the weight should you wish, by using the sportier of the three driving modes), but because its weight builds progressively from the start of every turn, it still endows you with heaps of confidence.
Rather like that of the Mercedes CLS, the adaptive suspension’s Comfort mode allows the Gran Coupé quite a lot of float to help it deal with gently heaving roads in a relaxed fashion. If you fancy a bit more control, simply pop it in the midway Sport or most extreme Sport Plus mode and it’ll hunker down without becoming brittle.
Sharper ruts cause it to jolt more abruptly, but nothing like as badly as the CLS can. Our car had the optional M Technic Package, which includes lower-profile tyres that may have exacerbated this behaviour, so, if you enjoy a supple ride, test drive an 840i without that package added.
Also, try an A7 Sportback if you’re less bothered about handling prowess. It’s one of the Gran Coupé’s most cosseting rivals, and not only for ride. It’s quieter at motorway speeds, with less wind and road noise, although the Gran Coupé keeps those at bay just as well as a Panamera or CLS.