Mercedes-AMG GLS 63 review

Chassis upgrades over the standard GLS are focused on the speed-sensitive electro-mechanical steering, adaptive air suspension and brakes, which use 400mm steel discs in combination with six-piston calipers up front and 370mm rear steel discs with single-piston floating calipers at the rear.

AMG Dynamic Select offers two additional drive modes on top of the familiar Comfort, Sport, Sport+ and Individual. Choose Trail or Sand and ground clearance is raised by 55mm and the engine and chassis settings are adapted for off-road driving.

Heading the exterior styling changes is AMG’s Panamericana-style grille, part of a newly designed front bumper with a more pronouced splitter element. Standard-fit LED headlights, flared wheel arches, a larger diffuser and twin chrome tailpipes complete the more aggressive look.

How does the GLS 63 perform on the road?

Driving the GLS 63 on the public highways of our US test route is lesson in moderation. Few seven-seat luxury SUVs have the ability to erupt off the mark with such athleticism and then go on to reach such high speeds with all the potency of a pure-bred sports car. And you’re constantly reminded of it by the flashing speed limit sign function.

It’s the deep reserves of torque, boosted as they are by the integrated electric motor, that give the new AMG its bounding performance. It is omnipresent at anything above 1500rpm and propels the big SUV along with the sort of effortlessness matched by only the best of its rivals.

With a short application of the throttle in one of the more performance-orientated driving modes, you’re already well down the road before you know it and the sheer speed is accompanied by a lovely deep baritone rumble from the exhaust.

The efforts of the engine are well backed up by the gearbox, which picks off ratios in much more determined fashion than the unit used by the standard GLS.   

It’s not all about seat-pinning acceleration and sheer speed, though. When you wind back the pace and choose the Comfort drive mode, the GLS 63 becomes a capable long-distance cruiser. Even on the optional 23in wheels, there’s still a degree of compliance to the ride that other performance SUVs fail to deliver in their most relaxed driving mode. On part-throttle loads in higher gears, it’s wonderfully refined, too.

AMG has gone to extensive engineering lengths to ensure the dynamic potential of the GLS 63 improves on standard versions of the third-generation GLS. And it shows.

The adaptive dampers stiffen in steps through the Comfort, Sport and Sport+ modes. The air springs also automatically reduce the ride height by up to 20mm in both Sport and Sport+, and when your speed extends beyond 75mph. It drops by 10mm in Comfort mode, too.

In addition, active engine mounts help to control load forces, stiffening through corners to provide a firmer base for the GLS 63’s mighty powerplant and then relaxing again to better disperse road shock through the structure on the straights. Electronically actuated active roll bars firm up to counter roll as lateral forces increase, then loosen to help keep the ride pliable at the straight-ahead.

Given its weight and size, it’s incredibly agile along winding roads. It's perhaps not quite as nimble as some rivals sporting four-wheel steering, but the precision and control is definitely a big step up on the old GLS 63 and sufficiently engaging to be described as entertaining.

The 4Matic four-wheel drive system operates in combination with a standard electronic limited-slip rear differential. The apportioning of drive is predominately to the rear until greater grip is required, at which point up to 50% can be fed to the front wheels. The upshot is outstanding traction and purchase.

What upgrades have been made inside the cabin?

Inside, the cabin has received the traditional AMG treatment, with AMG-specific instruments, infotainment functions, steering wheel, front seats and trim elements. It’s high on quality and its twin 12.3in displays, which work in combination with the German car maker’s latest MBUX user interface system, deliver suitable high-definition traits. But the GLS 63 lacks the bespoke feel of some high-end SUV rivals, feeling and looking a bit too similar to that of the smaller GLE 63 in many areas. It’s commodious, though, with the capability of accommodating up to seven people in three rows of seats, with 355 litres of luggage space, or five people in two rows and an 890-litre cargo area.