Mercedes-AMG GLS 63 2021 review

If your preferred automotive symphony takes the form of a shockingly agile, shockingly enormous three-row family SUV with a four-litre twin-turbo petrol V8 engine, you’ll regard the 2021 Mercedes-AMG GLS 63 as a masterpiece.

And even if this veritable apartment block on wheels isn’t really your genre of car, one spirited drive would be enough to leave you quietly awe-struck.

While the underlying Mercedes-Benz GLS-Class large SUV isn’t especially blunt to drive, AMG’s chassis-fettling experts have done quite a number on the latest GLS 63.

How does the AMG GLS 63 drive?

The AMG GLS 63 formula is a simple one. Take the largest SUV that Mercedes-Benz build, the hand it off to the brand’s AMG performance specialists for some invasive surgery.

If it’s going to be transformed into a proper AMG vehicle, the roomy, lush, three-row GLS needs to be faster and firmer everywhere. Sitting above the GLE 63 five-seater in the fast Benz SUV lineup, the GLS 63 starts from an opulent base.

The standard GLS, which can be had with six-cylinder petrol and diesel powertrains in Australia, is perfectly acceptable luxury family transport with an emphasis on softness and effortless, relaxed progress.

Once AMG are done refitting a GLS 63, though – from its hand-built, hold-out petrol V8 engine to the heavy adjustments to the standard air suspension and total ride and handling package, it’s a different animal.

Just like any other 63-badged AMG vehicle – currently the hardest-core cars Affalterbach builds – it all kicks off with a pronounced bark from the quad exhaust tips when you touch the glowing Engine Start button.

It’s a command that fires AMG’s in-house four-litre twin-turbo petrol V8 engine into life. In this application, the motor produces 450kW of power – 603 horsepower – and 850Nm of torque. The four-litre follows AMG’s one builder, one engine philosophy, and the cover is appropriately signed.

The GLS 63 is the first AMG vehicle to usher in a 48-volt mild hybrid electrical architecture that provides short-term boosts of up to 16kW and 250Nm more. The mild hybrid setup also enables a four-cylinder coasting mode along with genuinely refined auto start-stop capabilities.

In concert with the nine-speed torque converter automatic and the rear-biased all-wheel-drive system, the conventionally and electrically boosted V8 is good enough to fire the GLS 63 from 0-100km/h in just 4.2 seconds.

Given the 5.24-metre long, 2.03-metre wide GLS 63 weighs in at 2,710kg, that’s quite a feat, speaking volumes about the traction developed by the standard-fit Michelin Pilot Sport 4S tyres that measure a very wide 325mm at the rear.

The rapid straight-line speed also speaks to the GLS 63’s 4MATIC all-wheel-drive system, which allocates torque in a 50/50 split front-to-rear in normal conditions, but is actually capable of diverting 100% of available torque to the rear wheels alone.

That said, it’s the GLS 63’s ability to punt down a twisting country B-road while imbuing the driver with reasonable confidence that is the truest display of what AMG can do to transform a car.

Despite being compliant enough in town, the GLS 63 feels noticeably more rigid than the standard car. Some of it is traditional hardware – the air suspension is tuned to considerably constrain wheel movement – but there’s plenty of modern wizardry at play.

The same 48-volt integrated starter generator that provides extra torque to the engine also powers the almost instantly responsive, fluid-filled active engine mounts that can stiffen up on demand to lock the 200kg-plus V8 down during fast cornering.

There’s sharper and quicker turn-in than you’d expect – though the Michelin rubber makes a substantial contribution here. Michelin’s Pilot Sport 4S tyres represent just about the best road rubber on the market right now – though at close to four figures per corner in this size, the replacement costs are high.

We’re not going to pretend the GLS 63 turns into AMG’s halo GT coupe in the corners: it doesn’t. There’s still plenty of mass to move here, but the combination of a stiff body, brilliantly constrained wheel movement via the air suspension and the GLS’s high-voltage trickery keeps this large SUV well in check.

Turning off twisting country lanes and back onto suburban streets, we found the GLS 63’s Sport damper setting to be most appropriate. Usually we’d recommend Comfort on large wheels, but Sport stops the ‘63 from feeling boaty while never causing bumps to crash through to the cabin.

A word on ride quality: we’d recommend sticking to the standard 22-inch wheels. They’re massive and look great, and the ride they deliver (in Sport) isn’t unrefined. Step up to the 23s and there is a harder edge – and more worryingly, the test car we drove on 23-inch wheels had developed one or two rattles in the cabin, probably from the harder ride.

It’s also worth noting this is a very quiet car at speed – it relaxes just as much as it can shock. Despite the power on tap, if the exhaust is in its more reserved setting, you hear only muffled sensations from the V8 engine.

The GLS 63 is a safe car, too, but the semi-autonomous aids can be switched on and off with a one-touch menu. The lane centring is strong, but if you are punting this big bus down a narrow lane, you’ll want to switch it off. We were impressed by the smoothness of the active cruise control, which has dispensed with the usually jerky acceleration and braking characteristics of systems like this.

How is the AMG GLS 63’s interior?

The latest GLS has taken a significant step forward over its predecessor in terms of interior quality.

Your eye will immediately be caught by the new interior design, dominated by huge, twin 12.3-inch screens, resembling other late-model Mercedes-Benz products.

But it’s actually the way the cabin is screwed together that has received the most attention. The old model wasn’t exactly poor in this regard, but as a whole, Mercedes-Benz quality has been on a gradual lift, and the latest GLS has benefitted from this change in attitude.

These cars have always been about supple leathers and cold metals, but it’s the way the panels meet with thin, consistent panel gaps that really matters. It’s the absence of rattles – aside from the car with the too-big 23-inch wheels – and the aura of being hewn from granite that buyers look for at this level.

For the most part, the new GLS 63 impresses in this regard.

The AMG-specific seats are trimmed in a combination of black and grey Alcantara and nappa leather, and they look and feel pretty good – though they are quite wide set. Bigger frames will feel immediately comfortable, but narrower types will look for the (missing) bolster inflation controls.

Seat heating and cooling is standard up front, though, and both are appreciated given Australia’s recent temperature extremes. And the driving position is high, affording a very commanding view out.

AMG’s latest steering wheel is an intimidating unit with a large diameter and a huge array of controls: trackpads for remotely commanding either screen before you, active safety controls, and AMG’s take on a Manettino dial for the car’s drive modes – and two further customisable buttons for quick-access functions like start-stop, damping, exhaust loudness, and stability control (for the brave).

In our test car, the wheel was trimmed in Alcantara and gloss-covered carbon fibre – part of the interior carbon package ($4,200) – and it looked and felt great. We still prefer leather on a steering wheel to Alcantara, which doesn’t have hard-wearing properties. The metal paddle shifters are a great touch, though.

Now, about those screens. The GLS runs Benz’s MBUX infotainment system, which is richly featured and mostly intuitive to navigate. Many elements are terrific: the satellite navigation graphics are cartographic in their maturity, while the media page’s Apple Cover Flow-esque album artwork display is quite captivating.

But there are some really simple functions that are way too hard here. Changing a music track shouldn’t be difficult, but it is – requiring a precise stroke on the ‘fast forward’ touchpad. And unlike in a BMW X7 or Audi RS Q8, there is no wireless Apple CarPlay or Android Auto. When you do plug in your phone, CarPlay is not allowed to take full advantage of the screen, either.

It’s hard to dislike the industrial design here, though, with a handsome array of rectangular air vents and a broad muscularity to the sweep of the dashboard. No doubt, there’s a sense of occasion inside the GLS 63.

We will point out, though, that the lower you look in the front of the GLS, the harsher the plastics get – to the point that the bottle holder skins are rock hard and scratchy: in other similarly-priced vehicles, this is soft – or even leather-lined!

Moving to the second row demonstrates the sheer size of this beast: at over 5.2 metres in length, it’s palatial back here. Six-foot adults fit with so much room to spare – even the third row in this vehicle was designed to accommodate somebody measuring 6’4”, the brand says.

Leather-lined and truly spacious, the GLS is an ultimate road trip machine, and it only gets better by adding the rear seat comfort package ($2,800) that adds extensive electric adjustment for the individual outboard seats and a tablet located in the centre console.

A rear seat entertainment package ($6,300) goes further, adding dual screens mounted behind the front pews, along with a television tuner and wireless headphones.

Access to the third row is reasonably simple, with one-touch seat fold and slide controls, though the kerbside access is on the wrong side, designed for Europe or the United States where this car is built. And it’d be so much more graceful if the GLS 63 sported separate captain’s chairs in the second row.

Still, once kids (or adults) have squeezed past the folded second row it’s reasonably roomy, and in the wayback you’re still protected by curtain airbags and have access to air vents and cupholders.

Finally, behind a fast-action power tailgate the GLS 63 has heaps of boot space, even with all three rows in place, where it provides a hatchback-like 355 litres. In five seat mode, the GLS 63 offers 890 litres, and in two seat mode you get a van-like 2,400 litres. Folding the seats is done electrically, of course, while there is a space saver spare crammed beneath the boot floor.

What are the AMG GLS 63’s running costs?

It shouldn’t be a surprise that running a hugely powerful, petrol V8 seven-seat SUV will be a costly endeavour.

When you consider the complexity of the engine and many of the components that make this crossover so rapid, it’s also natural that the servicing costs will be quite high. And they are.

Mercedes-AMG are quite generous with the service intervals, which are annual or every 20,000 kilometres – whichever comes first.

You can also save a considerable amount by purchasing a service plan up front. This costs $3,050 for three years, which AMG says represents a saving of $950. A four year pack costs $4,000, while a five year pack will set you back $4,550. That’s an average of about $1,000 per year if you prepay.

The addition of a 48-volt mild hybrid system, as well as a more efficient four-litre V8 that replaced the old car’s 5.5-litre unit, means fuel consumption is not as bad as it once was for the GLS 63 badge.

AMG claims fuel economy of 13L/100km for the 2021 GLS 63. There is a good chance of achieving this (or better) on the highway where the engine will shut down one bank of cylinders – but day-to-day driving is likely to sit around the 20L/100km mark.

The GLS 63 is covered by the same five year warranty as other Mercedes-Benz and Mercedes-AMG vehicles.

Among German luxury car brands, this is relatively good, as BMW and Audi have not followed a move from three to five years of coverage – but among mainstream brands, a five year warranty is the norm.

The final verdict

The AMG GLS 63 is totally excessive. That’s the brief.

Truly fast in a straight line and remarkably capable in the bends, AMG have created quite a show-stopping family car in the third-generation GLS 63.

With only a few missing details that caught our attention, this is a well-rounded family vehicle that doubles as something of a missile when you want it to.

Still, we’re left with a niggling feeling that in the future, this formula will be served by electrified vehicles. There’s a feeling that the rate at which the GLS 63 chews through consumables will not be in vogue forever.