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2021 Mercedes-AMG GLS 63 Test Drive: Patience Required

The SUV that turns the entire world into a roadblock.

Aaron GoldWriterManufacturerPhotographer

SHERMAN OAKS, California—If you are not 100 percent positive that you are the most patient, forgiving, unflappable, easy-going person in the world, then please, please, please do not buy a Mercedes-AMG GLS 63.

If you have ever sat in your car, waiting to make a right turn as an old woman crossed the street with her walker, smiled kindly at her and thought to yourself how nice it is to see the elderly and infirm enjoying the fresh air, then had a little voice pop up in the back of your head—Geezus, can't the old bat move any faster?—do not buy a Mercedes-AMG GLS 63.

If you have ever wondered if your waiter—weighed down by a tray with six main courses, all smiles and working hard to earn every penny of the 25 percent tip you plan to leave—could maybe set those damned dishes down with just a smidge more haste, do not buy a Mercedes-AMG GLS 63.

If, while listening to your beloved children enthrall you with the latest tales of preschool politics, amazed at the spectacular process of your offspring learning to interact with the world around them, you had the slightest, tiniest, microscopic-sized inkling, which of course you would never ever in a million years act on, to say, "Oh, for f--- sake, just get to the point already!", then do not buy a Mercedes-AMG GLS 63.

If you have ever shown the slightest deviation from 100 percent perfect politeness and civility, this is not the car for you, because the world is a very different place when one is at the wheel of a king-sized SUV with 603 twin-turbocharged horsepower. Everyone else—and I mean everyone else—is in your way.

2021 Mercedes-AMG GLS 63: Performance

Like a nuclear bomb, the GLS 63 is a device with an exceedingly narrow scope of purpose. It is not so much an SUV as a high-speed express train without tracks. Its sole purpose is to get seven occupants from Point A to Point B as quickly as comfortably as possible. It will accelerate to 60 mph in around four seconds and on to a top speed of 174 mph, and God help the poor saps ahead who cannot move as quickly—and that's all of them.

The dedication the GLS' engineers devoted to this one singular task is impressive, even allowing for the fact that they're German. The engine is a 4.0-liter twin-turbo V-8 producing 627 lb-ft of torque as well as the previously mentioned 603 hp. It also uses a 48-volt mild hybrid system called EQ Boost that adds 21 hp and 184 lb-ft. The high-voltage electrics provide near-instant engine starting and all-wheel drive ensures near-instant traction. There are even heating pads in the armrests and center console to provide near-instant warmth. There is no waiting in a GLS 63—at least not because of the GLS 63.

2021 Mercedes-AMG GLS 63: Interior & Equipment

The interior is the one indicator that there are some people at Mercedes-AMG who believe patience is a virtue. It's an oasis of leather and wood, designed so that neither finger nor retina shall find even the slightest fault in any surface. The $4,550 Burmester surround sound audio system does wonders with soothing classical music, and the optional Energizing Package Plus (at $550 it's basically free by Mercedes standards) combines massaging seats, ambient lighting, and perfumed air in order to keep the driver relaxed and calm.

Nice try, but it doesn't work.

2021 Mercedes-AMG GLS 63: Handling

It took me only a few pulse-quickening, temper-heating miles to realize that driving the GLS 63 AMG on the freeway is nothing but an exercise in frustration, so I headed for the serenity of my favorite canyon roads. I've driven enough high-end SUVs that I should no longer be amazed at their competence, but the GLS 63 turned my frustration to utter awe. It was like driving a sport sedan from a flybridge on the roof. Steering response is sharp. There is virtually no body roll. Acceleration and deceleration are heroic. And despite 23-inch wheels—that's only an inch less than the ones fitted to semi-tricks—and tires so low in profile that one wonders where the air fits inside, the GLS 63 AMG's ride remains steady and comfortable at all times.

Occasionally, I'd feel a momentary smidge of something—a incongruous sensation of pitch or float—that reminded me that I was driving a seventeen-foot, three-ton SUV. But then it was over, gone so quickly I could easily convince myself I had imagined it.

Mostly, what I felt was a sense of amazement that I could barrel into a corner with a little too much speed, knowing that the worst that would happen was some tire squeal and a little understeer. How far we've come from the early days of SUVs that felt like they'd flip over if you so much as glared at them. I never thought we'd see the day when big SUVs could keep up a pace like this. The GLS 63 might not be able to chase down a talented driver in a BMW M4, but it would certainly stay in the rear-view mirror far longer than that Bimmer driver might expect.

Most will credit the GLS 63's air suspension, but I'm pretty sure that there's a little black magic in there somewhere.

2021 Mercedes-AMG GLS 63: Problems

Flaws? I found a few. The transmission's Sport mode isn't nearly as aggressive as it ought to be. My guess is that Mercedes is relying on the low-end torque of the EQ Boost system, but when you boot the accelerator at low revs, there's a slight hesitation while the turbos (or maybe the electrics) come up to speed and the power comes on with a jerk. If you want to drive fast and smoothly, you must use the paddle shifters to keep the revs up. The reward is an engine note with definitive Biblical overtones—not the namby-pamby get-your-ass-out-of-the-garden-and-don't-eat-pigs parts of the Bible, but the really nasty bits with floods and fires and smiting.

Another glaring flaw is the interaction of the auto-hold and auto-stop systems. When you come to a rest in the GLS 63—or any Mercedes—you can give the brake pedal a sharp stab and then release it, and the brakes will stay on until you hit the gas. The auto-stop system will also cut the engine. (Most of my colleagues despise auto-stop, but I like it. Idling the engine at a stoplight is wasteful and unnecessary.) Thanks to the EQ Boost starter-alternator, the GLS' engine lights off instantly; you'll neither hear nor feel the starter engage. But when both systems are in use, the act of starting the engine, engaging the transmission and releasing the brakes results in a neck-snapping jerk. I found it nearly impossible to take off smoothly without disengaging one system or the other. Am I picking at nits? Perhaps, but nits like these can make driving even the most fantastic car—like the GLS 63—into a miserable experience.

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And it's not like your nerves won't already be frayed, because every curvy road eventually ends, and there before you are the mortals, few of whom are blessed with anything like the GLS 63. And how could they be? There is really no other SUV in its class. The Audi SQ7 comes up a hundred horsepower short, and the BMW Alpina XB7 trails the Mercedes by 37 lb-ft and lacks electric boost.

Should You Buy the 2021 Mercedes-AMG GLS 63?

I came away from my test drive with the utmost respect for the Mercedes-AMG GLS 63. It is exquisitely finished without veering into vulgarity, upscale without being ostentatious, and expensive but not outrageously priced. It's truly unlike any vehicle I've driven before—and in twenty-something years of doing this job, I've driven a lot. It's an amazing piece of road-going hardware.

But as much as I loved the GLS 63, I could never own one. I'm just not patient enough. And I've yet to meet anyone who is.