What is it?
BMW’s big coupe, now fitted with the 3.0-litre twin-turbo diesel engine. Given the praise that has been heaped upon each and every model to receive this excellent engine, it hardly comes as a surprise to discover that the award-winning unit has now found its way into the subtly facelifted 6-series.
What's it like?
As you slot the electronic key into the dashboard for the first time and hear the raw (if distant) chatter of a diesel, you can’t help but wonder whether the new 635d is such a good idea. Not for very long, though. One determined stab of the throttle is all it takes to wipe away any doubts.
The 635d comprehensively outguns the petrol-engined 630i and can scare even the V8 650i on occasion. On top of this, its combined average fuel consumption of 41mpg allows you to enjoy the performance without it threatening to empty your wallet, while giving it a range of more than 600 miles.
It is all achieved through a complex induction system that employs two turbochargers of differing size. The result is a specific output of 96bhp per litre, giving the 635d a generous 286bhp at 4400rpm. But it’s the torque that really steals the show; there’s 427lb ft at just 1750rpm, and 369lb ft of that can be tapped from as low as 1250rpm.