Mercedes GLS review

There are big cars, there are really big cars, and then there’s the Mercedes GLS. This 5.2-metre long, 2.0-metre wide behemoth is designed to seat seven people in comfort and is the flagship of Mercedes’ extensive large and luxury SUV range – think of it as an S Class SUV, if you will. 

As far as rivals are concerned, the GLS is closest in concept to the 5.1-metre long BMW X7. However, as a prospective buyer, you might also want to consider (slightly) smaller seven-seaters such as the Audi Q7, the Land Rover Discovery and the Volvo XC90, or if you only need five seats, the full-fat Range Rover. 

Right now, there’s only one engine on offer for the core GLS: a 3.0-litre six-cylinder diesel that brings a 400d badge. There is, however, the performance-focused Mercedes GLS 63 with a 4.0-litre V8 that is designed to take on the mighty X7 M50i, while the extravagantly luxurious Mercedes-Maybach GLS 600 (which has the same V8-engine) has its sights set squarely on the Bentley Bentayga and the Rolls-Royce Cullinan. 

In the GLS 400d, no matter which of the three trim levels you choose, you get a nine-speed automatic gearbox, four-wheel drive and air suspension as standard. Plus, the interior is finished to the same kind of level as you'll find in the Mercedes S-Class limousine, and Mercedes also offers semi-autonomous tech to make driving easier and help keep you safe.

You can even specify your GLS with an off-road package if you want to venture off the beaten path – although, let’s face it, cars of this type are rarely asked to tackle more than a slippery National Trust car park. 

In this review, we’ll look at everything from what the Mercedes GLS is like to drive, to how practical it is compared with rivals and how much it will cost you to run. Or, alternatively, to see how much we can save you on a new GLS, check out the deals available through our New Car Deals pages. It lists plenty of new luxury SUV deals.

The Mercedes GLS is a very heavy car, tipping the scales at almost two and a half tonnes. But thanks to the huge amount of low down grunt generated by that 3.0-litre diesel engine, it builds speed effortlessly; it’ll cover the 0-60mph dash in a swift 6.0sec (recorded at our private test track). However, while you certainly wouldn’t describe that as slow, it’s not as quick as the 5.6sec that the BMW X7 xDrive40d clocked in the same sprint.

As with the X7, there can be a small delay before the GLS’s automatic gearbox responds when you ask for a sudden burst of acceleration. However, this is nowhere near as obvious as it is in some other rivals – we’re looking at you, Audi Q7 – and the GLS’s shifts are suitably smooth most of the time.

Engine refinement also impresses; in fact, it’s easy to forget that you’ve got a diesel under the bonnet. And, while the car’s big tyres generate a bit of road noise, wind noise is very well controlled – especially when you consider the size of the hole that the GLS is punching through the air.

Instead, it’s the way the car rides and handles that disappoints for a luxury SUV. No matter which mode you select for the air suspension, the GLS tends to wobble about like a jelly on a spin dryer, and this is especially bad news for any passengers prone to travel sickness.

What’s more, it doesn’t exactly glide over bumps and potholes. Not only does the rival X7 offer a more controlled and comfortable ride, but it’s also better at disguising its bulk in corners, combining superior body control with more precise steering.

Like most big SUVs, the GLS will more frequently be seen traversing shopping centre car parks than rocky rural landscapes, but it should be able to cope easily with deep snow and cambered icy surfaces, particularly if you specify the optional Off-Road package, which brings low-range gears and tailored off-road driving modes. That said, if you are planning on venturing off the beaten path on a regular basis, make sure to take a look at the utterly fantastic Land Rover Discovery – what it can do off-road is simply staggering.

You sit very high in the Mercedes GLS, giving you a great view of the road ahead. Plus, the driver’s seat electrically adjusts every which way to help you get comfortable, and a standard 360-degree camera makes the GLS easier to manoeuvre in tight spaces than you’d expect.

On top of all this, the interior has more of a wow factor than the BMW X7 thanks to two 12.3in glass-fronted screens that sit side-by-side to create a panoramic effect, as well as swanky ambient lighting in a choice of 64 colours.

However, despite featuring metal detailing, real wood and swathes of leather, the interior doesn’t feel anywhere near as solid as in the X7 or the Audi Q7. Indeed, the air-con control panel on the GLS’s dashboard feels particularly flimsy, and some of the hard, scratchy plastics on the doors aren’t what you’d expect to find on a luxury SUV.

The infotainment system does impress, though. The menus are pretty logically laid out, and you can also use a Siri-style ‘Hey Mercedes’ voice control system, which recognises natural speech so you don’t need to learn specific commands. Apple CarPlay and Android Auto come as standard.

Most functions are operated by swiping and pressing either the left-hand screen or a touchpad between the front seats, although this is more fiddly to use than the X7’s rotary controller. But the GLS’s infotainment screen is more responsive than the ones you’ll find in the Q7 and Volvo XC90 and, unlike those cars, it has conventional climate controls that can be operated via physical buttons without taking your eyes off the road.

There’s masses of space for the front two occupants in the Mercedes GLS. What’s more, the second row lets three adults sit side-by-side comfortably, there’s little danger of their knees brushing the seats in front, and head room is superb despite the GLS featuring a panoramic sunroof as standard.

The GLS also offers third-row passengers easier access and more knee room than they get in the Audi Q7 or Volvo XC90, although six-footers will still want to encourage those in the second row to slide their seats forward a bit. But no matter which seat you’re sitting in, you’ll enjoy as generous an amount of space as you would in the cavernous BMW X7.

With all seven seats in place, there are still 355 litres of boot space, which is almost as much as you get in a VW Golf. And when the sixth and seventh seats are electrically folded flat into the boot floor (again, that functionality is standard) there’s easily enough room for two large pushchairs or all the suitcases you’re ever likely to want to carry.

As a bonus, the luggage cover can be used in both the five and seven-seat configurations, and you can store it under the boot floor when it’s not needed. With five seats in place, you can fit a whopping 10 suitcases into the boot, while an 11th suitcase fits in the underfloor storage – matching the X7’s capacity.

The Mercedes GLS is expensive even by luxury SUV standards (a Land Rover Discovery will seat seven in comfort for less money, and if you only need five seats then the Audi Q7 is cheaper still and a much better all-rounder). And although it’s no more pricey than the BMW X7 xDrive40d and big discounts are available, the X7 is a better buy, being more enjoyable to drive, more comfortable and just as spacious. You can check the latest prices on our New Car Deals pages.

You do get a lot of equipment for your money in the GLS, though. Even entry-level AMG Line Premium trim features keyless entry and start, heated front and second-row seats, 22in alloy wheels and a head-up display that projects key information onto the windscreen to reduce the need to take your eyes off the road (and isn’t available as standard on the X7).

That said, you may be tempted to step up to AMG Line Premium Plus trim because this brings massaging seats, heated armrests and semi-autonomous driving tech that’s designed to take the strain out of motoring when it comes to adjusting your speed, steering, changing lanes, braking, or moving off in traffic jams. Premium Plus Executive gets a few more luxuries, such as a heated steering wheel, a dashboard wrapped in Nappa leather and heated third-row seats, but we don’t think it’s worth the extra outlay. 

Unsurprisingly, the GLS is in the top BIK company car tax group. Meanwhile, it’s not as economical as equivalent Q7 or X7 diesels.

The GLS is too new to have proven its dependability but Mercedes finished 26th out of 31 manufacturers in our 2020 What Car? Reliability Survey – behind BMW (9th), Volvo (16th) and Audi (22nd), but ahead of Land Rover (last).

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