New Mercedes GLS review

There are big cars, very big cars – and the Mercedes GLS. This 5.2-metre long, 2.0-metre wide behemoth is designed to seat seven people in comfort and is Mercedes' flagship SUV. Think of it as an S-Class that's expanded upwards rather dramatically. 

There should be a version of the GLS to suit anyone (well, anyone with a six-figure sum to spend). Core models are offered alongside a performance-focused Mercedes-AMG GLS 63 and the extravagantly luxurious Mercedes-Maybach GLS, which has its sights set squarely on the Bentley Bentayga and Rolls-Royce Cullinan.

You can even specify your GLS with an off-road package to allow you to venture out on to tricky terrain – although, let’s face it, cars of this type are rarely asked to tackle anything more challenging than a stately home car park on a rainy day.

As far as rivals are concerned, the GLS is closest in concept to the BMW X7 and the long-wheelbase version of the Range Rover. However, as a prospective buyer, you might also want to consider (slightly) smaller seven-seaters such as the Audi Q7, Land Rover Discovery and Volvo XC90. 

So, is the latest Mercedes GLS good enough to rank among the best seven-seat SUVs available? Read on to find out...

So far, we've driven the latest Mercedes GLS in 450d form. Its 367bhp 3.0-litre diesel engine has a huge amount of low-down grunt, which allows this two-and-a-half tonne car to build speed effortlessly.

With an official 0-62mph time of 6.1 seconds, the 450d is almost as quick as the rival BMW X7 xDrive40d 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, it's nowhere near as obvious as in some other rivals – we’re looking at you Audi Q7 – and the GLS’s shifts are smooth most of the time. The GLS is not available with a manual gearbox.

Refinement isn’t quite as impressive, though. Wind noise is very well suppressed (especially when you consider the size of the hole the GLS is punching through the air), but the car’s big tyres generate some road noise. The 450d's engine is far from harsh-sounding, but there's more noise than in the equivalent X7 or Range Rover.

The GLS's ride is the main disappointing aspect for a luxury SUV. No matter which mode you select for the air suspension, it fails to glide over bumps and potholes with any grace, especially when fitted with 23in wheels. Occupants will feel and hear the abrupt thumps as the suspension bears the impacts. A Range Rover is much softer, while an X7 offers a more controlled and comfortable ride. 

At least the firm suspension means the GLS stays relatively upright when cornering at moderate speeds. The steering is a bit more meaty and feels more precise than a Range Rover’s but an X7 is the most resolved at disguising its bulk in corners, combining superior body control with more responsive steering.

Like most big SUVs, the GLS will frequently be seen traversing shopping centre car parks rather than rocky rural landscapes, which makes it more of a shame that it lacks the four-wheel steering system available with the X7 and Range Rover. As a result of its huge turning circle, it's much trickier to manoeuvre at low speeds and will feel more cumbersome to thread through narrow roads.

It should be able to cope easily with deep snow and cambered icy surfaces though – especially if you specify the optional off-road package, with its low-range gears and tailored off-road driving modes. That said, if you're planning to venture off the beaten path, consider a seven-seat Range Rover (or Land Rover Defender) too.

Alongside the 450d, there are three other engine options – the 450 petrol, which gets 375bhp, the performance-focused AMG GLS 63, which has a 603bhp 4.0-litre petrol V8 and the 550bhp petrol in the Maybach GLS.

Driving overview

Strengths Punchy performance

Weaknesses Not as hushed as rivals; firm ride is far from relaxing

You sit very high up 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 comfy, and its standard 360-degree camera makes it easier than you'd expect to manoeuvre into tight spaces.

The interior has a good level of wow factor thanks to two 12.3in glass-fronted screens that sit side-by-side to create a windscreen effect. It's all bathed in an abundance of swanky ambient lighting in a choice of 64 colours. The driver also gets a head-up display that projects key information on to the windscreen.

However, despite featuring metal detailing, real wood and swathes of leather, the GLS doesn’t feel as solid inside as an Audi Q7 or BMW X7. Indeed, some of the hard, scratchy plastics on the doors aren’t what you’d expect to find on a luxury SUV with a six-figure starting price.

The infotainment system does impress, though. The menus are 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. Android Auto and Apple CarPlay smartphone mirroring are included as standard.

The infotainment touchscreen is within easy reach when you want to operate it by touch and is more responsive than the ones in the Q7 and Volvo XC90.

You can also operate it by swiping on a touchpad between the front seats. It's more fiddly to use than the X7’s rotary controller but is a useful feature and far more precise than the small touch-sensitive pads on the steering wheel. Unlike most of its rivals, the GLS has proper buttons for adjusting the climate-control settings.

Interior overview

Strengths Easy to use controls; all versions come with electric seat adjustment

Weaknesses Disappointing build quality in some areas

There’s masses of room for the front two occupants in the Mercedes GLS. What’s more, the second row lets three adults sit side by side comfortably with little danger of their knees brushing the seats in front. Head room is superb, despite the standard panoramic sunroof.

Third-row passengers get easier access and more knee room than in an Audi Q7 or Volvo XC90, although six-footers will still want to encourage those in the second row to slide their seats forwards a bit. 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 355 litres of boot space, which is almost as much as you get in a VW Golf. When the sixth and seventh seats are electrically folded flat into the boot floor, 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 carry-on suitcases into the boot, while an 11th suitcase fits in the underfloor storage – matching the X7’s capacity.

Practicality overview

Strengths Will comfortably fit seven occupants; useful boot capacity

Weaknesses Some might prefer the BMW X7 and Range Rover’s split tailgate

The Mercedes GLS is expensive, even by luxury SUV standards, with the entry level AMG Line Premium Plus costing significantly more than a mid-spec BMW X7 xDrive40d with a few options added. A long-wheelbase Range Rover with seven seats costs even more though.

There are smaller alternatives (such as a Land Rover Discovery) that will seat seven in comfort for less money, and if you only need five seats, the Audi Q7 is cheaper still and a much better all-rounder.

You get a lot of equipment for your money in the GLS. The entry-level AMG Line Premium Plus trim features 22in alloy wheels, keyless entry and ignition, ambient lighting, rear privacy glass, a panoramic glass roof, heated front and second-row seats and massaging front seats.

You might be tempted to step up to Business Class trim because this brings a bit more luxury for those sitting in the second and third rows. It adds ventilated and massaging middle row seats, heated third-row seats, a heated steering wheel, sunblinds for the rear door windows, a pair of screens mounted on the back of the front seats and a rear tablet to control all the functions. You also get 23in wheels. 

The AMG GLS 63 4Matic+ Night Edition comes with lighter 23in alloys wheels, AMG exterior styling, a sports steering wheel and a sports exhaust system.

The two Maybach versions – which take the price towards £200,000 – come with their own design of 22in alloy wheels, Maybach logos and electrically extending side steps. The top-level First Class trim adds active-body suspension, folding rear tables, a refrigerated compartment and individual rear seats.

All versions of the GLS are in the top BIK tax bracket for company car drivers and the engines are not as fuel-efficient as the X7 or Range Rover equivalent.

The 2024 GLS has yet to prove its dependability but Mercedes finished 24th place out of 32 car makers in our 2023 What Car? Reliability Survey – behind Volvo (ninth) and BMW (12th) but ahead of Audi (26th) and Land Rover (28th).

Costs overview

Strengths Well-equipped; wide range of trims

Weaknesses More accomplished cars are available for less

For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here