Past Master Revisiting the revered BMW M635 CSI
A debonair grand tourer with the heart of a supercar, the BMW M635 CSI is hard not to fall in love with, as Alex Robbins finds out
It’s crisp to drive yet its underlying heft makes it more at home the faster you go
Full disclosure here: the BMW M635 CSI crouching in front of me in the Autocar car park has a bit of an unfair advantage right from the off. As an owner of a classic 6 Series myself, I’m already smitten before I’ve even grasped the stiff metal door handle, opened the wide door and descended into the narrow, well-bolstered driver’s seat.
Still, the chances are that you, dear reader, are somewhat predisposed to a fondness for this car, too. It’s hard not to be. The shape grows more elegant by the day, its cut-back nose thrusting forward of the delicate glasshouse and tapering tail end.
Bias aside, then, I think we can agree that any 6 Series is a pretty car. But this one isn’t just any 6 Series: the M635 CSI came into existence as a result of some rather bold lateral thinking by BMW, which involved inserting the 3453cc straight six M88 motorsport engine used in the M1 supercar into the 6 Series’ svelte body. Rarely, if ever, has a grand tourer been party to an engine of such raw motorsport breeding, but the result proved compelling.
Inside, a jutting slab of crackle black plastic veers toward the driver in the traditional BMW style, garnished with full-width vents where it meets the windscreen. There are some glorious 1980s touches, such as the check control panel with its LEDS that inform you of light bulb failures and low fluid levels, and the calculator-esque fuel computer.
But we’re not here to gawp at the dashboard. The M635 CSI – this one is BMW UK’S own D-reg car – feels docile as it gets under way, its ride relatively pliant, although the stiffened dampers give it less waft than a standard 6 Series. The pay-off for that comes at the first set of corners you come to, where it rolls less than the regular car, if not quite by the order of magnitude you might expect. Indeed, there isn’t the dramatic difference in character between a modern M car and its cooking-spec basis. The M635 CSI feels like a fettled version of the standard car in many respects.
There is one respect, of course, in which it feels very different: that engine. Oh, wow – what a thing. Low down, it’s laden with torque, responsive to even the slightest touch of the throttle. Give it its head, though, and it charges harder the greater the flogging you give it, its steely, full-throated wail filling the cabin as only a motorsport-derived straight six can. The ceaseless power is nerve-tingling, but it’s the noise that makes the whole experience feel like manna for the soul.
Indeed, the engine sits astride the experience of driving this car – like a hit of brandy in an already wellflavoured dessert. That extra potency is what makes the whole thing as memorable as it is.
What this is not is a super-coupé as we might think of it today. It doesn’t quite have the breadth of talent to hurl you around on a twisting road, to shock you with instant, thumping performance or to involve you in the experience of driving it so much that you realise you’ve spent the past 15 minutes gripping the wheel and perspiring gently.
Instead, it remains true to its roots as a grand tourer: crisp to drive, yet with an underlying heft that makes it more at home the faster you go. Drop a cog on a straight bit of autobahn, though, and the M635 CSI transforms, for just as long as you pin the throttle, into a full-blown 1980s supercar.