What's it like?
Mercedes has long been a connoisseur of the six-cylinder diesel and based on the GLC Coupé's, that remains the case. It fires to a creamy idle, revs smoothly and delivers luxurious waves of torque that make steep inclines and motorway overtakes superbly relaxing. Merc's nine-speed torque converter moves between its many gears intelligently enough by itself, too, and isn't too far behind paddle pulls.
UK cars will come with passive Sport suspension as standard while for £1495 you can add adaptive air suspension - as fitted to all of our test cars. The result feels a different beast than offered by BMW or Porsche; with the emphasis more on comfort than outright agility. And that's no bad thing because our car stayed settled over ruts in town and felt supremely cushioning on the motorway, more so than its rivals.
The GLC Coupé's steering has been made slightly quicker than the GLC's and switching from Comfort to Sport driving mode gives it extra weight, as well as making the gearbox snappier, the throttle more responsive and, (in our case), the suspension stiffer. Ultimately, you've got to be pushing extremely hard on the road before the front wheels start their journey wide, but the GLC Coupé never invigorates like a Macan.
The GLC Coupé's steering is fairly precise, but lacks the Porsche's razor-sharp, linear feel and you're aware of the Mercedes' weight shifting laterally through a series of bends that bit more too. If anything, our experience of the lighter-nosed 250 d on the same test drive event showed a slightly keener turn-in, even if it was still less urgent than its rivals.
But I'm not sure that's such an awful thing. The 350 d is brilliant at shutting out outside noise, while in the tallest of its many gear ratios its V6 is allowed to sink to a hush at a motorway cruise. Sat on air suspension, the GLC Coupé does quiet comfort even better, and that will count for a lot for many.
The theme continues inside, where the driver is treated to a good, high driving position, with generous seat and wheel adjustment. Those in the back get about the same head room as in an X4, but probably a little less than in a Macan, while leg room is similar across the three. On paper, its 500-litre boot matches BMW and Porsche's efforts, but the X4 and GLC (unlike the Macan) suffer the same raked roofline and therefore hindered practicality.
The Mercedes holds it own for perceived quality, its switchgear and dash materials just about out-gunning the BMW and coming very close second to the solid but svelte Porsche. Our car's cabin was enhanced further by a £1395 Premium Plus Equipment Line, which adds Merc's larger-screened 8.0in Comand Online infotainment and beautifully crafted Burmester sound system.
That said, the fact that a smaller-screened Garmin-based sat-nav infotainment, rear parking sensors, man-made leather seats, keyless start, a reversing camera, LED headlights, heated front seats and electronic tailgate all feature on every GLC Coupé might mean you don't need to begin the box ticking.
Should I buy one?
We'll leave whether or not it looks the part up to you, but if you value comfort and refinement before driver engagement then the GLC Coupé has a lot going for it. Who knows, a drive of the standard-sprung version may move it closer to the Macan dynamically, but we doubt it will ever surpass it without AMG getting involved.