This is the 6-Series that everyone will buy, so it's just as well the 640d is the best model in the range. Well done, you 90 per cent of purchasers, for you have made the right decision. Unfortunately, if you like driving, this isn't saying much.
As we've reported before, BMW's glitziest coupe is no 911-chasing sportster. In fact, despite the lack of doors and lower roofline, imagine Merc CLS or Audi A7 as potential competitors (ironic, given that next year the 6-Series will spawn a four-door derivative), or alternatively think of it as a more practical Jaguar XK. Like them, it delivers no fuss, waft-o-matic progress.
And this is why the diesel works so well. It's as noiseless as it needs to be, nicely quick without ever feeling like it's trying too hard, and although the claimed mpg is predictably optimistic, we happily got over 40mpg, which means 600 miles between fill-ups. It's a typically lovely engine to use, although we do wish that BMW would desist from playing fast-and-loose with the badging - it's the exact same unit as in the 535d.
And it's often hard to tell exactly what the twin-turbo six cylinder is up to. Although the eight-speed auto shifts imperceptibly, it spends so much of its time changing gear that you don't get a feel for how the engine actually behaves unless you use the paddles. This is worth doing, simply to savour the torque, which peaks at 1,500rpm and sustains the full force of 464lb ft for pretty much the rest of the rev-counter needle's arc. Fourth gear provides a pretty impressive demonstration of what the 640d is all about.
But this is an engine for wide open roads. Impressive though it is, it doesn't have the instant response and energy needed to hammer out of slow corners. And although you can tell it drives through the rear wheels, the question is whether you're bothered. You should be, but, honestly, you just aren't. You see the 6-Series has a highly accomplished chassis - you turn the wheel, and it tracks where it's asked, with no fuss or delay. But driver interaction is lacking, there's no feedback through the steering and a nagging sense that the car is just going through the motions.
Of course, it's very quiet and comfortable and rides rather nicely, even when wound into the sportiest of the £3,400 Adaptive Drive's five modes. It also has a thoroughly agreeable cabin (although the rear seats are quite restrictive) and it looks pretty sleek, too. But shouldn't a BMW coupe be more dynamic than this?
We like: A very comfortable, relaxing GT car
We don't like: A very comfortable, relaxing GT car
The verdict: BMW tones down the 6. Now more than ever a car for the golf-club set.
Performance: 0-62mph in 5.5secs, max 155mph, 51.4mpg
Tech: 2993cc, 6cyl, Rwd, 309bhp, 464lb ft, 1735kg, 145g/km CO2
Tick this on the options list: Comfort seats, £1,485
And avoid this: Active steering, £1,220