Happily, given that you can’t get the diesel yet, the gas-powered 2017 GLS 450 is a good bit more fuel-efficient than the previous model: Where the 2016 GL 450 was rated 15.2 / 12.6 L/100 km (city/highway) Mercedes-Benz’s documentation has the new rig coming in at 14.4 / 11.4 L/100 km. In terms of actual fuel consumption, my test vehicle was showing a long-term average of 16.8 L/100 km when I picked it up, and the best I saw was 12.4 L/100 km on a 40 km mixed highway/suburban run – not bad for a vehicle that can haul seven people in comfort and tow 3,500 kg (7,716 lb). Adding a bit of extra expense at the pump is the fact that the turbocharged V6 requires premium fuel.
Heading up the retuned ride dynamics for 2017 is a new Dynamic Select controller that allows you to adjust the powertrain and suspension settings to suit your driving style and road conditions. The default Comfort setting provides the calm, unflappable (if slightly ponderous) ride and smoothly powerful acceleration you’d expect from a big Mercedes-Benz. Flip into Sport mode and the suspension firms up, the throttle response becomes more eager and the transmission mapping more aggressive (you might almost say perhaps a little too aggressive). It’s a pretty striking Jekyll-and-Hyde transformation, and the GLS 450 is impressively taut and responsive feeling for such a large vehicle when in Sport mode – indeed, it becomes downright fun, if a bit of a guilty pleasure. Additional modes include a snow mode, a rough-terrain mode, and an Individual mode, which was my favourite as it allowed me to firm up the ride without engaging the overeager Sport throttle and transmission mapping. Regardless of the mode selected, the GLS remains exceptionally solid feeling, and wind noise is well-damped (although I did notice a little bit of tire hum from the big 21-inch Continental Cross Contacts).
Inside, the 2017 GLS 450 is properly comfortable and accommodating, with roomy and supportive front seats, plenty of space in the second row, and room for real-size adults in the third row provided the second-row seats aren’t reclined all the way back. Cargo space is 453 L behind the third-row seats (295 L under the cargo cover), 1,399 L behind the second-row seats, and 2,656 L with all seats folded.
Interior materials include a stitched leather-look dash topper, soft-touch front and rear door uppers, soft-skinned console sides and cloth-wrapped roof pillars, and my test car raised things up a notch further with gorgeous-looking optional ($250) open-pore ash wood trim. Parts like the door lowers and cargo liner are rigid plastic, as expected, but perhaps less expected in this segment is that the standard seat upholstery is man-made Artico (“artificial cow”) leatherette. Real leather is available, of course (it’s a $1,990 option), although the Artico leatherette looks convincing enough that I thought it was genuine leather for the first couple of days.
The new touchpad controller is cantilevered above the traditional rotary control knob, and it recognizes smartphone pinch and swipe gestures. Truth be told, my peanut-sized brain found the splitting of input duties between the touchpad and the rotary controller to be a little confusing and awkward, but I’m sure with time it would become second nature (heck, even I eventually adapted to the combined use of a mouse and keyboard, so why not?)