Mercedes GLS review

The Mercedes GLS takes a huge leap on from its predecessor, boasting superb comfort and refinement while offering more space than nearly anything else for the money. Its diesel engine is smooth, powerful and quiet, delivering fuel economy which – though not great – is acceptable for this sort of car. We think E-Active Body Control is a must-have option to allow the GLS to operate at its best – the ride quality is sublime.

It’s not quite as special to drive or travel in as the similarly priced Mercedes S-Class, however – the dash looks too much like the cheaper GLE’s and refinement isn’t quite on the same level. It’s also huge; potentially too big for most UK roads and definitely for the city roads most will inevitably frequent. These nit-picks aside, the GLS is a great car overall.

On its launch, Mercedes dubbed its GLS as ‘the S-Class of SUVs’. That’s a tough billing to live up to, especially when you consider the peerless reputation of the brand’s most luxurious saloon.

It’s made an even tougher task given the broad spread of abilities the GLS needs to cover. This is a car which needs to not only carry as many as seven adults in the sort of luxury that S-Class passengers would expect, but also give a decent account of itself off road – whether drivers ever bother to take it there or not.

The GLS follows on from the previous model (which before a renaming strategy in 2016 was simply known as the GL), but this is possibly the closest to S-Class-on-stilts travel yet. It also sits at the top of a huge Mercedes SUV family, which kicks off with the GLA and climbs through to the GLB, GLC and GLE (the latter two are also available in sleeker ‘Coupe’ model lines), plus the iconic G-Class and all-electric EQC.

While the previous GLS platform could be followed all the way back to 2005 and the M-Class SUV, the current model shares it underpinnings with the latest GLE. With a structure that’s both lighter and more rigid than before, it helps Mercedes to deliver superb refinement. It also enables the brand to install the latest and fanciest version of its MBUX infotainment system, plus a host of advanced safety tech.

The GLS family kicks off with the AMG Line Premium trim. Standard kit includes 22-inch alloy wheels, a 360-degree camera and a panoramic sunroof. Above it sits the AMG Line Premium Plus: it costs around £8,000 more, adding massaging climate-controlled front seats, heated front and rear armrests and a rear seat entertainment system. The AMG Line Premium Plus Executive trim features 23-inch alloy wheels, climate-controlled rear seats, a heated steering wheel, nappa leather trim and additional wireless mobile phone charging in the rear cabin.

There’s only one standard engine: a 3.0-litre V6 diesel matched to a nine-speed automatic gearbox. However, for those in need of more power there's the Mercedes-AMG GLS 63 4MATIC+, which employs a 4.0-litre V8 engine to deliver 603bhp. It's available in Night Edition or Night Edition Executive trim.

There’s one car that Mercedes has clearly pitched itself towards: the BMW X7, another imposing SUV that delivers space and refinement for up to seven people. The Range Rover Sport is also similarly matched on price, but it can’t compete with the Merc’s rear seat space. Above the GLS price-wise – but unable to match its seating count – are the Bentley Bentayga and the Rolls Royce Cullinan.

On the road, the GLS gets very close to Mercedes’s claims of an ‘S-Class of SUVs’. Refinement is excellent and performance is more than adequate, so overall it’s a very relaxing, comfortable place to while away the miles.

As standard the GLS comes with air suspension, but its real party trick comes with the Advanced E-Active Body Control suspension set-up. This employs two cameras that scan the road ahead to prime the suspension in order to cancel out any ruts and bumps.

Without this system, the GLS can occasionally thump into large bumps, the body rocking across cambers and undulations; it falls short of the X7 in terms of both comfort and control. With it, however, the ride quality and body control are just sublime.

E-Active Body Control can make a difference in the corners, too. In its normal setting, it helps to fight against body roll, leaving a stable platform at all times. However, switch to ‘Curve’ mode and it can actively lean into the corners. It’s at its best on motorways and fast, flowing A-roads, where it gives the feeling of a high speed train. However, on very twisty sections the system struggles to keep up. Regardless, the GLS feels is stable, predictable, and offers up strong levels of grip. The steering is light and precise.

It’s quiet on the move, too. The most audible noise at speed comes from the tyres, but this isn’t a criticism: it’s just that everything else is so quiet. A fairly slippery shape (at least by SUV standards) means that wind noise is well suppressed, while the engine only really makes itself heard when you ask for hard acceleration.

One area where the GLS falls short of the X7, however, is manoeuvrability. The BMW is available with four wheel steering, which makes town driving remarkably easy for a car of this size. Without it, the GLS feels rather cumbersome by comparison.

Engines, 0-60 acceleration and top speed

From launch, the GLS UK range has only one standard engine option: the 400 d, powered by a 325bhp 3.0-litre V6 diesel. It copes easily with the near-2.5 tonne mass it needs to haul about thanks to a hefty 700Nm of torque delivered from as little as 1,200rpm. It allows the GLS to cover the 0-62mph sprint in 6.3 seconds and achieve a top speed of 148mph.

It’s also remarkably quiet on the move and, although not quite as hushed as in an S-Class saloon, emits only a distant rumble under hard acceleration. It’s mated to Mercedes’ nine-speed automatic transmission, which for the most part goes about its business unnoticed.

One car that certainly won't go unnoticed is the the Mercedes-AMG GLS 63 model, which takes performance on to supercar levels. Its 4.0-litre V8 petrol engine produces 603bhp and a colossal 850Nm of torque. 0-62mph is dispatched in 4.2 seconds, and the top-spec Night Edition Executive version will power on to 174mph.

There’s only so much a combustion engine – no matter how efficient – can do to offset the need to haul around a 2.5-tonne SUV. So while the 3.0-litre V6 diesel is a capable unit, at best it achieves 30.7mpg in official WLTP tests. Spend time driving in town and that number is likely to drop quite significantly. Despite the relative thirst, an enormous 90-litre fuel tank means that, should you match the official economy figures, the GLS will cover about 600 miles on a tank.

The Mercedes-AMG GLS 63, trading economy for extra performance, is only able to achieve a maximum 22.1mpg.

Prices for the diesel-powered GLS start from just over £75,000 and climb to around £92,000 before options. You'll need deeper pockets in order to be able to climb into one of the AMG versions, with the top-of-the-range GLS 63 Night Edition Executive version priced at an eye-watering £128,285.

Insurance groups

With such a hefty price tag, insurance costs aren’t likely to be cheap. Groupings for the GLE head right to the top of the 50 classifications available, so a big budget will be needed beyond the initial purchase price.

Depreciation

Depending on the trim level, the GLS is predicted to hold between 43 and 49% of its value over three years and 36,000 miles. That’s some way behind the BMW X7, which retains up to 56% over the same period.

To get an accurate valuation on a specific model check out our free car valuation tool...

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While the BMW has gone for an imposing, borderline obnoxious look for its X7, the GLS looks fairly understated – or at least as understated as it’s possible for a 5.2-metre long SUV to be. It has lost the chunky, boxy shape of the previous version for an altogether sleeker design, while features like the grille, headlights and front bumper are reshaped to differentiate the face from the smaller GLE.

All versions ride on wheels measuring at least 22 inches, so while it could never be called pretty, the proportions do appear neat and clean. There’s nine exterior colours to choose from: the Emerald Green paint finish shown in these images is a particular highlight.

Inside, the GLS’s dashboard is lifted almost wholesale from the smaller GLE. The large central sweep of wood (or aluminium) trim houses the air vents, while above it there’s Mercedes brilliant twin 12.3-inch MBUX infotainment set-up. The interior is a lovely place to spend time, but for the brand’s top of the range SUV we would’ve liked a little more differentiation in design from the smaller car. As you’d imagine, the interior colour options are fairly subdued, ranging from blacks and browns to lighter beige upholstery.

Sat-nav, stereo and infotainment

The GLS uses Mercedes’s latest MBUX infotainment system, which here is made up of two 12.3-inch screens sitting side-by-side. The first screen, sat ahead of the driver, is a customisable display that shows driving information in a variety of layouts, and can also offer a mix of navigation and entertainment functions. These can be adjusted through touch sensitive controls mounted on the spokes of the steering wheel.

The second screen is the main infotainment unit. This shows the navigation functions in much greater detail and, thanks to touch-screen input, allows the driver to pinch and swipe across the map to both preview destinations and adjust the zoom. It’s also the location of the 360-degree camera’s display and, when equipped, the augmented navigation system, which superimposes live instructions onto images relayed from a forward-facing camera.

The system looks gorgeous and is easy to use. The home page is laid out in a tile-like format, and the large display makes the icons easy to read. While so many functions are controlled via the touchscreen, the climate functions are still adjusted by physical buttons below.

While it’s a slick system, users can still rely on their smartphone apps if they prefer: all models come as standard with Apple CarPlay and Android Auto.

Rear seat passengers are catered for when it comes to tech, too. All versions of the GLS can be enhanced with a pair of 11.6-inch touch screens mounted on the back of the front seats, allowing middle row passengers to browse the web or watch a film.

The GLS appears in just the one body style; unlike its GLC and GLE stablemates, there’s no option of a fastback-like ‘Coupe’ option here. Buyers can choose between six or seven-seat layouts, with the former offering individual seats for a VIP shuttle feel.

As you’d expect, the high ride height gives a commanding view of the road ahead, although it’s not quite as high as the G-Class’. For such a large car, the large glass area all round makes visibility fairly good, and for the areas which can’t be seen easily, a 360-degree camera is standard.

The GLS is a class leader when it comes to space. All three rows of seats can easily fit tall adults, while there are generous door bins and plenty of other storage areas dotted around the cabin.

Dimensions and size

The previous GLS was hardly a compact car and the current version expands to even greater dimensions. At 5,213mm long, it stretches 83mm further than the old GLS, and 62mm more than the BMW X7, too. Including the door mirrors, the GLS is 2,157mm wide (it’s 2,030mm wide to the edge of the wheels – 30mm more than the X7) and it’s 1,823mm tall. The wheelbase measures 3,135mm.

For those who plan to tackle fords and river crossings in the GLS, wading is possible in up to 500mm of water. Impressive, but less than the Range Rover’s 900mm figure.

Leg room, head room & passenger space

If passenger space is the number one priority, then look no further than the GLS. Many cars offer space for seven, but in reality the rear seats are only good for children. Not so the GLS: in the third row, Mercedes claims that anyone up to six feet four inches tall will fit just fine. Those seats are heated, too, and each have access to their own USB charging points. They may seem a long way behind the driver, but thanks to a microphone system, it’s still easy enough to hold a conversation without raised voices.

Buyers can have the GLS with either six or seven seats. That means a 2-2-2 configuration which includes individual captain’s chairs for the middle row, while the 2-3-2 configuration uses a more conventional middle bench.

The three-seat option feels like it loses little in plushness though, particularly if the optional Rear Comfort Package Plus is equipped: this allows the centre seat to fold down into a wide armrest, featuring a removable tablet for controlling the comfort and entertainment functions. The middle seats can slide and recline and, like those in the back, offer acres of head and leg room.

The GLS is the perfect place to carry kids, and plenty of them: four ISOfix locations mean that there’s plenty of choice when it comes to child seats.

Boot space

The vast exterior dimensions translate to not just impressive passenger space, but plenty of load-carrying ability too. Even with all seven seats in place, the GLS boasts a 470-litre boot; 80 litres more than the old car, 144 litres more than the BMW X7 manages, and comfortably bigger than the average family hatchback. Drop the third row and volume grows to 890 litres, while in two seat mode there’s 2,400 litres on offer. Each of the five rear seats can be lowered at the flick of a switch, and save for a slight angle on the middle row, lie completely flat.

The huge rear door makes access easy too, and the air suspension can be dropped slightly at the rear so it’s a little easier to load heavy objects. A parcel shelf can be fitted behind the third row to hide away certain items and when it’s not in use there’s space to store it beneath the boot floor

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Towing

You’d expect the GLS, complete with a torquey diesel engine, advanced air suspension and a long, stable wheelbase, to be an excellent tow car – and you’d be right. Rated to tow a braked trailer weighing up to 3.5 tonnes, the GLS also features a system called Trailer Assist. All the driver needs to do is select an area on the touchscreen in which to position the trailer, and the system instructs the required steering inputs to achieve them. In our experience – with a driver who had never towed a trailer previously – it was very intuitive to use.

Euro NCAP hasn’t tested the Mercedes GLS but it has tested the closely related GLE; given that the pair share so much mechanically, it’s reasonable to speculate that the two will perform similarly.

And that’s a good thing: the GLE achieved the maximum five star rating when it was assessed in 2019. It achieved a 91% score in the adult occupant protection category; a rating that puts the Merc two percent ahead of the BMW X5 (a car which shares much with the X7). A child occupant protection score of 90% is excellent; indeed the only car to achieve a higher score in 2019 was Mercedes’s own CLA (it scored 91%). The GLE scored 78% in both the vulnerable road users and safety assist categories.

AMG Line Premium Plus and AMG Line Premium Plus Executive models come as standard with what Mercedes calls the Driving Assistance Package Plus. This includes a host of advanced safety tech, including extra sensors to allow for part-autonomous driving functions for motorway driving. It also adds “PRE-SAFE Impulse Side”, which, using the wide range of external sensors, helps to mitigate damage in side impacts caused by other vehicles by using active seat elements to position the occupants in a manner that reduces the risk of injury.

Meanwhile, smaller bumps can be avoided thanks to the standard 360-degree parking camera and the optional automatic parking function.

Mercedes finished 28th out of 30 manufacturers in our Driver Power customer satisfaction survey, with running costs and overall reliability being key points of concern.

Warranty

Mercedes offers a three year, unlimited mileage warranty with each of its cars. Some manufacturers offer longer warranties now, but this cover is a match for what BMW offers and superior to Audi’s, which is limited to 60,000 miles. It’s also possible to pay extra for an extended warranty.

Servicing

Servicing at a franchised Mercedes dealer can come at a cost. However, it can be made more manageable by the brand’s ServiceCare package: this encompasses two services in two years, three services in three years or four in four years, all for a fixed monthly fee. Service intervals are set at every 15,500 miles or once a year, whichever comes first.