Three trims are available – AMG Line, designo Line and the AMG breathed on GLS 63. The entry-level model gets 21in alloy wheels, adaptive air suspension and LED headlights, a panoramic sunroof, a sports braking system and an aggressive AMG bodykit on the outside, while inside there is a 360-degree camera, tri-zone climate control, heated seats all round, a Harman and Kardon sound system, and Mercedes-Benz’s 8.0in infotainment system with DAB radio and Bluetooth connectivity.
Upgrade to the more luxury appointed designo Line and your GLS gains Mercedes’ active curve system, limiting body roll and increasing agility and safety. There is also ventilated and massaging front seats, four-zone climate control, temperature-controlled cupholders, rear sunblinds and a luxury quilted leather upholstery.
Looking for more speed in your life then the GLS 63 may very well be the answer with its aggressive bodykit, high-performance braking and exhaust system and AMG-embossed sports seats to go alongside the 5.5-litre V8 at the front. In this test we sampled the mid-range model with the default diesel motor on UK roads.
If there’s one word that sums up the GLS, it’s 'massive'. Compared with an Audi Q7, the Mercedes is longer, taller and a bit wider. Although that might sound like a recipe for disaster on our tiny island, the GLS comes as standard with a 360deg camera system that makes manoeuvring surprisingly easy. The boxy body also helps.
On the move the V6 is as smooth and refined as you’d hope from a luxury SUV, no doubt helped by its sub-2000rpm cruise. Sure, when pushed you do hear it, but it’s not an unpleasant noise which avoids the more strained sound of a Q7’s V6 diesel.
Over larger bumps and undulations, the GLS strikes a fine balance between comfort and body control at speed, largely avoiding the floaty feeling you get from some air-suspension systems. You do pay a price for standard-fit 21in wheels though, with expansion joints and potholes thumping through the car's structure.
Designo Line benefits from clever anti-roll bars that all but eliminate body roll in the bends. Although this masks the bulk of the GLS to a point, you do feel the car’s mass if you push harder, especially during braking.
The steering is precise enough but is missing any real feedback, even when put into Sport mode. The suspension also gets a Sport setting, which firms it up significantly. You feel much more of the road but it seems pretty pointless considering the absence of roll in Comfort.
Step up into the cabin and you’re treated to a commanding view of the road over the long, vented bonnet. There’s ample room to stretch out for all occupants in the first two rows while even adults in the rearmost seats shouldn’t complain too much. Compared with rivals such as the Range Rover Sport, there’s noticeably more space for third-row occupants.
Although the boot is relatively small with the third row up, the seats fold electrically into the floor as standard. Do this and you’ll open up a vast cargo area, but fold the middle row down too and there isn't much you couldn’t fit into the rear of the GLS.
It’s not all good news though. Considering that Mercedes bills this as ‘the S-Class of SUVs’, some of the interior doesn’t feel as plush as you’d hope. While there are plenty of nice leather and metal trimmings, there’s a surprising amount of creaking plastic and buttons which have come from much lower down in Mercedes' range. Next to the considerably cheaper Audi Q7, it’s disappointing.