What is it?
Despite the new name, the GLS isn’t, strictly speaking, a new car. Instead, it’s a facelift of the Mercedes GL-Class that’s been around since 2012. The oily bits have largely been left alone, apart from the adoption of a new nine-speed automatic gearbox for the 3.0-litre V6 diesel, which makes up the vast majority of sales.
Although the engine still produces the same 255bhp, the extra ratios mean economy and emissions are improved. It’s also fairly brisk considering the 2.5-tonne heft of the GLS, with 0-62mph taking a respectable 7.8sec - a small improvement on the outgoing GL-Class. If you want to go faster, you can still get an AMG variant with a twin-turbo 5.5-litre V8.
The rest of the changes are cosmetic or simply make the GLS even more lavishly equipped than the GL-Class. Up front is a new nose that mirrors the rest of the Mercedes-Benz range, while the rear gets redesigned exhaust tailpipes. Inside is a new steering wheel and instrument panel and a redesigned centre console.
Three trims will be available in the UK: AMG Line (which gets more aggressive bumpers in keeping with the name), the more luxurious Designo Line and the rapid GLS 63 AMG at the top of the tree. We’ve sampled the mid-range model with the default diesel motor on UK roads.
What's it like?
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. Ultimately you can cover ground fairly quickly, but it’s not something the car or you will particularly relish.
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.
Should I buy one?
If you’re after a big, imposing SUV, there’s not much on sale that is either as big or, indeed, imposing as the GLS, save for the (more expensive) full-fat Range Rover of course. The problem is that while it’s decent to drive and has the looks on the outside, it feels underwhelming in places on the inside.
If you're after seven seats, we’d still take a look at the Range Rover Sport first, as it proves even nicer to drive for similar money. Alternatively, try the much cheaper Audi Q7; its interior is even better and it’s certainly not short on space.
Mercedes GLS 350d Designo Line
Location Suffolk; On sale Now; Price £78,095; Engine V6, 2987cc, diesel; Power 255bhp at 3400rpm; Torque 457lb ft at 1600-2400rpm; 0-62mph 7.8sec; Top speed 138mph; Gearbox 9-spd automatic; Kerb weight 2455kg; Economy 37.2mpg (combined); CO2 and tax band 199g/km, 37%