2021 Mercedes-AMG GLS 63 Review: Muscle Car Meets Large Luxury SUV

Do you really *need* 603 horsepower in your family hauler?

2021 Mercedes-AMG GLS 63
2021 Mercedes-AMG GLS 63

I’ll be the first person to admit that there really is no need for a massive three-row luxury SUV with over 600 horsepower and a 4.1 second 0-60 time. Bearing that in mind, I’m kind of glad this one exists. And for now, there is only one such beast on the road: the Mercedes-AMG GLS 63.

Why on earth would anyone want a car this big and this fast? After driving around in the GLS 63 for a few days, the effortless power combined with luxury and practicality became oddly addicting. A quick Costco run? Check. Easily beat that smug kid in the STI up the freeway on-ramp? No problem. Do both of these with your parents and the in-laws in the back, while getting a back massage? This SUV can definitely do the job.

2021 Mercedes-AMG GLS 63

But saying that the GLS 63 is fast is like saying that a cheetah runs fast. It’s actually quite entertaining to see the look on people’s faces when you stand on the throttle. The 4.0-liter V8 at the heart of the GLS 63 is simply a hammer of an engine. Although displacement is down from the 5.5-liter engine found in the previous generation, power is up by 26 for a total of 603 horsepower. Torque is even more impressive at 627 lb-ft. Helping to achieve these phenomenal numbers is a 48-volt mild hybrid system that contributes 21 horsepower and 184 lb-ft torque. However, it’s mostly used to help smooth out the power delivery and fill in for any turbo lag.

When not hammering the throttle, the GLS 63 is a smooth and efficient cruiser. Credit the mild hybrid system, which allows for coasting with the engine off, even at highway speeds. The integration is seamless, as I hardly noticed when the engine would restart with an application of the throttle. I was able to average around 20 mpg over several hundred miles, which is quite remarkable for a 6,000-pound vehicle with this much power.

Handling is impressive for such a large vehicle, but make no mistake, this is not a replacement for a sports sedan. Monster-sized Michelin Pilot Sport 4S tires on optional 23-inch forged rims offer up plenty of grip, but there’s only so much to be done when trying to fling a three-ton barge around a corner. Still, when pushed hard, she remains composed, and there’s less body roll than you’d expect. The suspension truly is comfortable in the comfort setting, if a bit floaty, and even the stiffest setting doesn’t make for an overly jarring ride.

On the inside, you’ll find an appropriately luxurious and comfortable interior. Standard features include massaging front seats and a huge panoramic sunroof. Soft leathers and other quality materials surround the cabin, except for the lower door panels, which feel more like rental grade plastic. It’s a bit hard to fathom why Mercedes is trying to save a few nickels with this cheap stuff, but luckily it’s barely noticeable.

There is a little less cargo space behind the power third-row seats than I expected, and passengers won’t enjoy much legroom. Someone looking for a truly spacious interior will have to settle for an Escalade or a Navigator, both of which have the GLS beat in terms of sheer size and volume.

Mercedes has thrown all of its latest tech at the GLS 63, including dual 12.3-inch infotainment displays and the new MBUX interface—which works quite well. One minor annoyance is an overactive suite of driver-assistance nannies. I made the mistake of driving a bit close to some cones in a construction zone, and the car threw a digital fit, with the front camera view taking over the screen, accompanied by loud beeping and flashing.

On the plus side, the optional high-end audio is provided by a simply fantastic Burmester surround sound system. This luxury item has to be one of the best sound systems available in a car and is worth every penny of the $4,550 price.

All in, our test car stickered at $149,115—which waters the eyes a bit, even given the level of performance and available features. Sure, the optional $1,500 carbon fiber engine cover is a bit excessive, but with a $132,100 starting price, the GLS 63 stands in the “if you have to ask…” territory. For similar money, you could buy a Chevy Tahoe and a new Corvette, but I doubt anyone shopping for a GLS 63 is weighing it out on value.

2021 Mercedes-AMG GLS 63

Apparently, the market for high powered large SUVs is also growing, as the GLS 63 will soon have some company. The BMW X7-based Alpina XB7 is coming this fall and brings 610 horsepower to the table. The Dodge Durango SRT Hellcat also comes out next year and ups the ante to an insane 710 horsepower. 600+ horsepower hellion SUVs on the market today include the Bentley Bentayga Speed, Lamborghini Urus and Jeep Grand Cherokee Trackhawk. Although some might say this is a sign of how ridiculous things have become, at least the race out of the Costco parking will be a lot more interesting.


  2021 Mercedes-AMG GLS 63 4MATIC
Base Price $132,100
Price As Tested $149,115
Engine 4.0L twin-turbo V-8 with EQ Boost
Power (hp) 603 hp @ 5750 – 6500 rpm
Torque (lb-ft) 627 lb-ft @ 1800-4600 rpm
Transmission 9-speed AMG Speedshift automatic
Electric motor 48V / 21 hp / 184 lb-ft
EPA Combined 16 mpg
Drivetrain Layout front-engine, all-wheel drive


Front: 4-wheel independent double-wishbone
Rear: multilink rear suspension based on AMG ACTIVE RIDE CONTROL


Four-wheel disc with ABS
0 – 60 mph 4.1 seconds
Dimensions (length x width x height) 206.4 x 79.9 x 70.2 inches (w/o mirrors)
Wheelbase 123.4 inches
Ground Clearance N/A
1st Row Legroom 40.3 inches
2nd Row Legroom 41.9 inches
3rd Row Legroom 34.6 inches
Passengers 7
Cargo Capacity Behind 3rd row 17.4 cu. ft.
Max Cargo Capacity (all rear seats folded) 84.7 cu. ft.
Curb Weight 5,798 lbs.
Tow capacity N/A