The first thing that strikes you about the GLS is the sheer size of the thing – it’s longer than a Range Rover – and some drivers may find that alone intimidating. Still, even the most basic (although that never seems like the right word in connection with a GLS) model comes in AMG Line trim, which means you get an AMG bodykit, 21-inch alloys and an aluminium finish to the running boards. You also get LED headlights and, in a neat touch, the Mercedes logo is projected onto the ground from the bottom of the door mirrors when you open the car. Externally, the only difference between the AMG Line and Designo Line cars is the different design of alloy wheels, while the top-spec GLS 63 has slightly different AMG bodystyling, as well as red brake calipers, twin chromed exhaust tailpipes and the option of 22-inch wheels. Wherever you take it the GLS is bound to get you noticed, but whether those stares come through admiration or disdain will depend on your audience.
In terms of its design, the GLS’s cabin is very much what you’d expect of a Mercedes. The build quality is excellent, with plenty of chrome detailing to liven up what is a predominantly black dashboard, but it’s not as classy an ambience as you’d find in, say, a Volvo XC90 or Audi Q7. Likewise, it’s all generally pretty easy to use, although the COMAND operating system isn’t as intuitive as BMW’s rival iDrive. As you would only expect, you sit very high up in the driver’s seat, with a great view of the road ahead; and, thanks to the huge range of adjustment on the seat and wheel, it’s easy for anyone to get comfortable. You might worry that parking such a beast would be very difficult because of the restricted view, but it’s much easier than you might expect, because every model comes with front and rear parking sensors, and a combination of four cameras that produce an all-round view on the centrally mounted screen on the dashboard – still, trips to a tight multi-storey are only for the brave.
It’ll come as no great surprise that a car as big as the GLS has plenty of room inside. On top of the generous room in the front seats, there’s an enormous amount of head- and legroom in the middle row of seats, with the huge doors making it easy to get in and out. Indeed, the middle row is set so far back from the front seats that the driver could struggle to turn round and reach anything they’ve left on the seats behind. Where the GLS scores over the likes of the Range Rover is not just that it’s a seven-seater, it’s that the third row of seats will accommodate a couple of adults in comfort. Better than that, you can do a lot of the folding of the rear seats electronically at the touch of a button, which makes it much easier to swap between the various configurations quickly and without the risk of slipping a disc in the process. Drop all the rear seats and you’re left with a nice flat floor, as well as a large and easy-to-load boot – which opens and closes at the touch of button on the key fob.
Ride and handling
This is the area in which the GLS’s sheer size most counts against it, as ultimately you can’t deny the laws of physics. On pretty much any road other than a dual carriageway or wide motorway – and especially in congested city streets – you’re conscious and probably wary of the car’s size. Threading it down country lanes is made all the harder by the unfortunate combination of a vast amount of play around the straight-ahead, and the lack of feedback in the steering. Worse still, in the base AMG Line car, the body rolls so much in corners that it accentuates any steering input, making it hard to keep the car exactly where you want it. This is a big, ponderous car, and in a succession of bends – even a relatively swiftly taken roundabout – it’s a combination that can leave passengers rather green around the gills. So, it’s welcome news that higher-spec models come with the Active Curve System (a costly option on the AMG Line model), which reduces the body roll and makes the car more agile. Even with it, though, the GLS is not as rewarding to drive as other seven-seat SUVs such as, say, a Land Rover Discovery or Volvo XC90. At least the standard air suspension gives a comfortable and refined ride – particularly on the motorway – as long as you keep the car in ‘Comfort’ mode. In ‘Sport’ mode on the AMG Line car, we found that the ride became too firm, especially at low speeds. We found the GLS was at its best when using the ‘Individual’ drive mode – giving you the throttle and steering response of ‘Sport’ mode, but keeping the plush and pillowy ride quality from the ‘Comfort’ setting.
The engine has to work hard to get two and a half tonnes of GLS rolling
The GLS comes with a choice of two engines, but by far the bulk of buyers will choose the 3.0-litre diesel unit in the 350d rather than the 5.5-litre V8 petrol engine in the GLS 63 AMG. On paper, the diesel is capable of hitting 62mph in less than eight seconds – which is very respectable for such a big car – but it certainly doesn’t feel that way on the road. On the contrary, the engine has to work hard to get two and a half tonnes of GLS rolling, so the initial response – which is not helped by the lethargic automatic gearbox – is slow. Things are better once you’re up and running, but, with the gearbox in Comfort mode, the pause as it swaps between gears is enough to set the car’s nose bobbing up and down in sympathy. The GLS 63, on the other hand, is a very different beast – and that’s an utterly appropriate word. Needlessly and, some might say, pointlessly quick (with an entirely believable official 0-62mph time of 4.6 seconds), this is a seven-seat SUV that will trade punches with the fastest and most extreme versions of the Porsche Cayenne for straight-line performance.
Even by the standards of prestige-badged seven-seat SUVs, the GLS is costly; and, it’s no surprise that such a big and heavy car results in some pretty hefty bills. The 350d’s average fuel economy of 37.2mpg is well short of a diesel XC90’s and bettered even by the V6-engined Range Rover, while the Merc’s CO2 emissions mean you’ll be paying tax at a very high rate. As for the GLS 63, its fuel economy is positively frightening: if our brief drive is anything to go by, you can expect 20mpg at best. At least one consolation is that the GLS should follow other Mercedes models and have decent residual values, helping to keep long-term running costs down.
It’s too early to comment with any certainty on how reliable the refreshed GLS will be, but the omens aren’t great: the previous-generation GL (the predecessor to the GLS) rates very poorly with Warranty Direct’s Reliability Index, while Mercedes sits well below average in the company standings. Partly this is down to the expense of any repairs carried out; but close to a quarter of all complaints were about the electrics, so we’d hope that this will improve.
Still, the engine is tried and tested in a wide variety of other Mercedes models, and only the nine-speed gearbox is relatively untested when it comes to the mechanical components. The standard three-year, unlimited-mileage warranty is pretty decent though, and can be extended for a price.
There’s a thoroughly impressive array of standard safety kit on every model
The GLS hasn’t been tested by Euro NCAP, but there’s a thoroughly impressive array of standard safety kit on every model. That starts with a long list of airbags (including one for the driver’s knees), but also includes Blind Spot Assist and Land Keep Assist systems, as well as Attention Assist, which warns a driver if it thinks they are becoming drowsy by monitoring how you’re driving and sensing any lapses in steering or unusual behaviour. On top of that, the Collision Prevention Assist Plus system warns a driver of a possible collision and, if no action is taken, can operate the brakes automatically, at city speeds. Raid the options list and you’ll find radar-guided cruise control, and a range of active systems that will take measures to avoid a crash if the car doesn’t think you’re aware of the situation.
The GLS is an expensive car, but it comes with a suitably lavish set of standard kit. Air suspension, three-zone climate control, leather upholstery, DAB radio, sat-nav, Bluetooth and a 14-speaker stereo are all yours on the standard car, without venturing to the options list. Step up to Designo Line, and you add a more sophisticated climate control system, smarter leather trim and the ‘active’ suspension system. Should that little lot still not be enough, Mercedes will be only too happy to show you the extensive list of extras, but fortunately several of the most attractive options are bundled up in packages. The Off-road package does what it says on the tin, while the Driving Assistance package includes various safety-related features, and the Entertainment package brings a pair of 8.0-inch displays integrated into the front-seat head restraints, as well as a DVD player and digital TV tuner.
Why you would buy the GLS over its more polished seven-seat peers is a very good question. Perhaps the simplest answer is that it’s the ultimate – at least in terms of size, space and price – model in Mercedes’ extensive line-up of SUVs. It’s also, should you require it to be, a fairly capable off-roader. However, you do have put up with quite a few compromises, but some people will be prepared to do exactly that for the space, status and wealth that owning a leviathan car like this non-too-subtly implies.