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2021 Mercedes-Benz AMG GLS - 63 It's Magnetorheological Review By Dan Poler

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By Dan Poler
Bureau Chief and Senior Editor
Rocky Mountain Bureau
The Auto Channel

Magnetorheological. \mag·ne·torhe·o·log·i·cal\ (adjective)

I will admit not knowing the meaning of this word; I had to look it up (for the record: A type of fluid that increases viscosity when exposed to a magnetic field, to the point of becoming nearly solid - thanks, Wikipedia). 

I came to the 18 letter word on the Mercedes-Benz website, used in the description of a standard feature of the 2021 AMG GLS 63 we took for a spin this week. The fluid is used in the computer-controlled dynamic engine mounts equipped as standard. 

And such it is with the 2021 Mercedes-Benz GLS 63: A technological wonder, in so many ways. 

Our tester was painted in Emerald Green, a deep dark color - it presents serene and sedate, belying it’s true nature as a rocket. Upon approach the initial impression is that of its size; sure, there are the pure dimensions: 206 inches long, 80 wide, almost six feet tall. But the size is intentionally accentuated by flared fenders over 22 inch wheels, its imposing, distinctive grille supporting a dinner plate of an emblem in the middle.

As you open the driver’s door, you’ll immediately notice seats are high up - it’s a bit of a hop up and over the bolster into the cockpit. Once you’re there, seats are buttery smooth, materials amazing. And there’s the displays - or as a colleague so eloquently expressed it, “holy screens, Batman.” The dash consists of two enormous displays end to end, each 12.3” on the diagonal. One in front comprises the instrument cluster, infotainment over to the right. 

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Start up and the engine purrs to life, the displays alight with information… Maybe too much so. There’s a bit of information overload - not terribly surprising for a vehicle of this sophistication but frustrating nonetheless. The instrument panel is endlessly configurable yet somehow always a bit overwhelming in its clutter. Where Mercedes Benz has really come through is in control of all of the available features. For any given feature or function to be configured, there are no less than three ways to do so: Central touchpad, touchscreen, and a pair of tiny touchpads on the steering wheel at 10 and 2. If a particular action is difficult to reach, there’s usually an easier way. After some experimentation the controls become intuitive as one begins to remember the sequences of points and clicks to get to what’s needed. A particularly nice touch: Control of performance and tuning particulars need not require digging through menus thanks to a series of buttons and dials at the 4- and 8-o’clock positions on the steering wheel. The buttons each have their own small display and are reconfigurable to quickly select performance parameters. 

An interesting option is available to further enhance controllability, called MBUX Interior Assistant: Although ours was not so equipped, the add-on uses an overhead camera to respond to driver and front passenger arm motions and gestures - turn a light on by pointing at it. 

Unsurprising in a vehicle of this class, the creature comforts are numerous. Let’s start with the heated armrests: In the first two rows, inboard and outboard armrests become warm along with the seats (and do so nearly instantaneously, thanks to a rapid heating feature). You’ll have to trust me here: A heated armrest is not a thing you’d ever give much thought to until you experience - and once you do, you risk wondering for the rest of your driving life why all cars don’t carry this convenience. 

A series of options combined in the “ENERGIZING Package PLUS” package make use of the massaging seats, cabin lighting, and in-cabin fragrance system (replaceable cartridge in the glovebox)  in combination to provide programs such as Refresh, Vitality, and Joy. It feels a little gimmicky, and I suppose it’s in the eye of the operator to determine whether, after running the program, they feel refreshed, revitalized, and/or joyful.

Also equipped is a Burmeister Surround Sound system. As a $4,550 option, it’s a splurge - but the 1,610-watt amp drives an outstanding spectrum of sound to 26 speakers throughout the cabin. 

The second row is very nearly as delightful a place to spend time as the first: The heated seats and armrests appear here too, seats are, of course, power adjustable for comfort. As one would reasonably expect for a vehicle of this class, even full-grown adults will find comfort more than adequate for longer trips. Additional option packages can enhance this comfort even further, adding in seat ventilation massage, wireless chargers, and a screen dedicated to controlling all of this luxury.

By contrast, the third row is ... less delightful, maybe to the point of unusable: It’s very, very cramped and will be a struggle after five minutes for anyone over four feet tall. 

For its powertrain, the GLS 63 is technically a hybrid - a small 48-volt electric setup contributes power alongside the V8. In Comfort Mode, the GLS 63 is quiet, mild mannered, nothing to suggest its true nature. But of course, it’s that true nature we’re here for: That Aufecht, Melcher, and Großaspach masterpiece. The hand-built 4-liter twin turbo V8 puts out 603 horsepower and an astonishing 627 lb-ft of torque, rocketing nearly three tons of curb weight to 60 mph in 3.7 seconds - well under the 4.1 seconds quoted by Mercedes Benz. The setup is nothing short of marvelous, with that deep exhaust note coming through at every moment. 

In a straight line the GLS 63 was a great deal of fun, but around corners it struggled somewhat - with more than ten feet of wheelbase, the back end tended to want to wander out of place, leading to a troubling feeling of insecurity. Our test vehicle was appropriately clad for the season in Pirelli Scorpion Winter rubber - but not for the weather. In the foothills west of Denver temperatures were warmer than average, with no snow on the ground. It’s possible this poor combination contributed to the feeling, but a vehicle of this size will never be a sport sedan.

There’s a pricetag associated with all of this, and it’s not small: It starts at $132,100. By the time our test vehicle completed its option load-out, it topped out at a sticker price just shy of $150,000. Those options are dizzying in their variety, and really add up. One must wonder why rear side airbags are an additional seven hundred dollars, or a system for precise delivery of wiper fluid another three hundred and fifty. There are larger expenditures as well: The Burmeister audio and 23” multi spoke wheels alone add up a bit under $10,000. 

In the end, however, it’d be tough to find more fun that also can haul around 7 not in comfort, but in luxury. The GLS 63 is an outstanding choice for the day to day in uncompromised luxury, and crazy fast and fun when you want it to be. 


2021 AMG GLS63
Engine Type: Handcrafted AMG Biturbo with EQ Boost
Engine Size: 4.0 Liter
Horsepower: 603
Torque (ft-lbs): 627 
Transmission: AMG SPEEDSHIFT TCT 9-speed automatic transmission
Wheelbase / Length (in): 123.4 / 206.4
Curb Weight (lbs): 5,798
Pounds per HP: 9.6
Fuel Capacity (gal): 23.8
Fuel Requirement: Premium unleaded
Tires: Pirelli Scorpion Winter; 285/45R22 front; 325/40R22 back
Drivetrain: AMG Performance 4MATIC+ All-Wheel Drive
EPA Fuel Economy - MPG
city / highway / combined / observed: 14 / 18 / 16 / 16
Base Price: $132,100.00
Price as tested: $149,740.00