Road test review: Mercedes-AMG GLS 63

Wednesday, 3 February 2021

The Stuff Top Luxury SUV for 2020 is the Mercedes-Benz GLS 400d.

MERCEDES-AMG GLS 63
Base price: $272,300
Powertrain and economy: 4.0-litre twin-turbocharged V8, 450kW/850Nm, 9-speed automatic, AWD, combined economy 13L/100km, CO2 299g/km (source: RightCar).

The GLS 63 is every bit as gargantuan as it looks in photos. And it looks massive.

Vital statistics: 5242mm long, 1934mm wide, 1947mm high, 3250mm wheelbase, luggage capacity 470 to 2400 litres, 22-inch alloy wheels.
We like: More tech than you’ll know what to do with, massive power, imposing road presence.

An AMG-tuned V8 is why you’ll want to drive the GLS 63 some of the time.

We don't like: Size makes urban driving a bit terrifying, expensive, kind of pointless?

The biggest, most luxurious vehicle Mercedes-Benz offers is the GLS and the most potent GLS is this, the AMG GLS 63. Is bigger really better in this day and age? Should a large SUV have a hi-po V8? Do people who can afford this really care?

Those chunky exhausts don’t let out the same bellow as AMGs of old, but they’re still pretty loud.

So… um… Why exactly is there a gigantic AMG SUV?

The GLS is already a thing, like it or not, may as well give it to AMG. They’ve done weirder things in the past.

Up front is standard AMG fare, including the sports steering wheel with a drive mode knob and dedicated exhaust/suspension buttons.

The Samsung tablet in the rear seats is standard kit on the GLS 63.

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Yeah, the GLS 400 d is probably the best of the two. But it doesn’t get this cool badge.

Being a member of the ‘S’ family, there’s a huge amount of on-board tech. I mean, the thing comes with its own Samsung tablet that can control the MBUX infotainment system, which means you don’t even need to tell your driver where you’re going. What, you drive yourself? Peasant.

Except you will want to drive yourself in this, at least some of the time. The 63 badge indicates this is a V8-powered machine, though no longer displacing 6.3 litres. That’s been the case for a while now but as a refresher, AMG’s current range-topping powerplant is a 4.0-litre V8 with two turbos nestled within the cylinder heads. It can be had in various states of tune but here it makes 450kW and 850Nm which, on it’s own, is really enough. But that sentiment doesn’t exist at AMG.

Here, as in other current high-end Mercedes models, the engine is supplemented by a 48-volt mild hybrid ‘EQ Boost’ system that does boring (but worthwhile) things like improve fuel consumption by letting the vehicle freewheel at high speeds by disconnecting the engine when in Eco mode. It also does fun things like reducing turbo lag to essentially nothing and temporarily adding more power and torque, to the tune of 16kW and 250Nm.

Other AMG-specific enhancements include a Nappa leather interior, Active Ride Control, special wheels, high-performance brakes, a performance exhaust system, a track pack (probably the biggest waste of time on this list) and a dozen-odd AMG design tweaks inside and out.

Right, so it’s a big, tech-laden SUV made faster and less comfortable. Am I missing something?

No, that's pretty much it. It’s definitely fast, hitting 100kmh from zero in 4.2 seconds, which is frankly insane for a sedan, let alone a hulking SUV like this. That’s largely due to EQ Boost adding that extra torque. And boy, it sounds angry getting there.

AMG has given the GLS 63 a system that lets off gunshots on the overrun and allows the V8 to roar. People living in the past will say it’s not as good as it once was, and it isn’t, but there’s nothing that can be done by the factory about that now. The days of deafening V8s are over.

The Active Ride Control (AMG-speak for adaptive suspension) means the GLS 63 can straddle the divide between comfortable Autobahn cruiser and the “sports’ part of SUV.

Sort of. Comfort mode is still somewhat harsh and physics is something even the most cutting-edge electronics can’t defeat. The sheer weight (the wrong side of 2.5 tonnes) of the GLS 63 often overwhelms the tyres and suspension, which also brings into question the Track Pack. I mean, why on Earth would you even consider bringing your SUV to the racetrack? Especially considering the GLS 63 costs close to $300k, at which point it’s almost expected you have something else in the garage better suited for sporty driving.

As an aside, there was a bit of road noise in the cabin, likely a result of the Michelin Pilot Sport tyres and the racier suspension.

So don’t drive it fast. Isn't that what it’s really for?

Well, that’s the thing. Being an AMG, it is inherently built to go fast. But, being a GLS, it doesn’t want to. It wants to burn miles in ultimate comfort.

I packed six friends into the GLS to fill every seat and everyone said head and legroom was fine. We also discovered the GLS has microphones built into roof around the front and rearmost seats, so occupants can talk to each other without screaming. Very swanky.

When cruising, the GLS 63 is lovely. Every seat in the seven-seater house gets mobile charge points, with the middle row getting seat heating as standard. The front passengers have heated and ventilated seats. Warming any of the seats also warms the corresponding arm rest. Although, weirdly, I could only find two cup holders in the middle row.

All GLS models are absolutely massive, which makes urban driving a waking nightmare. But on the open road, every model has Distronic active cruise control and all the other driver aids you expect. Which really begs the question…

That the best GLS is actually the 400d?

Beat me to it. The 63 is awesome in a lot of ways but a large luxury SUV needs to be as soft as possible. It should be able to drive halfway down the country before needing a refuel and it should NOT have a Track Pack. Everyone loves a V8 and AMG makes some of the best but the GLS doesn’t need one.

The AMG badge is a byword for performance and, as I mentioned, the GLS is simply too big for that. The 400 d doesn’t make any attempt at such a thing, and is cheaper to boot.

I should also say GLS 63 also drinks petrol like a marathon runner drinks water, not that owners will care about fuel costs. But it’s another reason to opt for the 400 d.

Really, the GLS should be electric. But, ideally, we really need solid-state batteries ready to go, in order to get similar range to the 400 d.

Any other cars I should consider?

The GLS’s natural rival is the BMW X7, but in AMG 63 guise you could also consider the Audi RS Q8 as a cheaper coupe-SUV alternative. Other large SUVs like the Bentley Bentayga V8 or Lamborghini Urus cost more than $300k, putting them into another category altogether.