Big, fast, wonderful.

The 2021 Mercedes-AMG GLS 63 is one of just a handful of high-end, three-row performance crossovers on sale today. It gets the company's biggest V8, the latest and greatest in-car tech, and swathes of leather, wood, and other high-end treatments inside, typical of what you expect of a high-end Mercedes-Benz crossover. But this three-row is focused on performance above all else.

And the Mercedes-AMG GLS 63 does everything as advertised and more. It's ridiculously quick, supremely upscale, and even pretty comfortable in the right setting. But that's not to say the GLS 63 doesn’t have a few minor drawbacks. Most notably, the GLS 63 sacrifices a bit around-town livability with such hardcore performance options, plus it costs an exorbitant sum, especially with options.

Pros

Silly Amounts Of Power

Silly Amounts Of Power

Powering the Mercedes-AMG GLS 63 is the same twin-turbocharged 4.0-liter V8 you get on virtually every other AMG 63 model, only here it pairs to a 48-volt mild-hybrid system known as EQ Boost. This setup produces 603 horsepower and 627 pound-feet, which propels the GLS 63 to 60 miles per hour in a ridiculous 4.1 seconds. That's right – by the time you finish reading this sentence, the 5,927-pound Mercedes has already reached 60.

And the Mercedes-AMG GLS 63 feels genuinely fast, not just fast for a three-row SUV. Twist the nifty steering wheel-mounted drive mode selector to Sport Plus, mash the gas pedal, and the GLS 63 accelerates with a ton of force. There's a whisper of turbo lag, but it's quickly quashed by the 48-volt mild-hybrid assist system, which delivers an extra 21 electric horses and 184 lb-ft.

And once you get higher in the rev range, that V8 shows how powerful it is by building power continuously all the way up through redline. Find a long enough stretch of road with no speed limits and you could theoretically top this thing out at 174 miles per hour. Imagine that: 174 mph in a three-row SUV.

Upscale And Advanced Cabin

Upscale And Advanced Cabin

The inside of the Mercedes-AMG GLS 63 is an extremely nice place to be. It ups the luxury ante over the base GLS with more standard features like Nappa leather (versus fake leather) and enhanced trim options on the dash, including a few from the Mercedes Designo specialty department. The seats in our tester wear handsome Tarufo brown-and-black leather combo, while the dash gets $1,750 in carbon fiber and the sport steering wheel has a $600 Dinamica finish.

Joining those upscale treatments are two 12.3-inch screens: a touchscreen dead center and a digital instrument cluster just behind the steering wheel, both housed within the same bezel. As with most Mercedes models, the GLS 63 runs the latest MBUX software with advanced features like “Hey, Mercedes” voice control, augmented reality navigation, and various ambient lighting and massage functions.

Comfortable Ride

Comfortable Ride

Yes, even with optional 23-inch wheels – the biggest you can get outside of the Maybach model – and low-profile tires, the GLS 63 is still pretty cushy on the road. Much credit goes to the adaptive air suspension in Comfort mode, which absorbs blows from even the most broken pavement and barely shrugs at aggressive speed bumps. Also thank the active anti-roll bars, who help smooth out undulations. Things get a little harsher in Sport and Sport Plus modes, but even then the ride isn't as backbreaking as some alternatives. Also helping further bolster our backsides are those big, cushy front buckets seats wrapped in Nappa leather – they're extremely supportive and offer both heating and cooling functionality.

Cons

Sport Mode All The Time

Sport Mode All The Time

The Mercedes-Benz GLS 63 is a very posh crossover, and as mentioned, in Comfort mode its adaptive suspension smooths out even the crudest pavement. But Comfort mode also dulls the throttle response and steering input too drastically. In this drive mode it takes a second for the GLS 63 to respond when you put your foot on the gas, and the steering feels lackluster.

We spent most of our time driving the GLS 63 in Sport mode, even around town. While that does make the suspension noticeably stiffer than what you get in Comfort mode, it improves steering feel and throttle response significantly. But if you really want to tailor your driving experience in the GLS 63, Individual mode allows you to configure some of these settings individually based on driving preference.

Pricey With Options

Pricey With Options

Alongside the GLS 63, the small list of big luxury performance crossovers includes the BMW Alpina XB7, the Tesla Model X Performance, the Range Rover SVAutobiography Dynamic, and that’s about it. At $132,100 to start, the GLS is competitively priced given that the Tesla starts at $99,990 and the most expensive option, the Alpina XB7, costs $141,300 to start. But the price tag on our tester is a daunting $153,035 post options.

The list of options on our GLS 63 tester includes $4,950 matte black 23-inch wheels, a $4,550 Burmester surround sound system, a $1,500 carbon fiber engine cover, a $600 Dinamica steering wheel, and a few others. Some of those options should come standard on a car that already costs six figures to start.

Unimpressive Fuel Economy

Unimpressive Fuel Economy

Even with EQ Boost hybrid assist, the Mercedes-AMG GLS 63 doesn’t get great fuel economy. The twin-turbocharged V8 achieves 14 miles per gallon city, 18 highway, and 16 combined. That’s noticeably less than the standard GLS, which gets up to 21 mpg combined, worse than what’s offered on the Alpina XB7 (17 combined), and matches the Land Rover SVAutobiography (16 combined). But of course, the electric Tesla Model X Performance beats them all with 305 miles of range.

Competitors

BMW Alpina XB7
Dodge Durango SRT Hellcat
Land Rover SVAutobiography Dynamic
Tesla Model X Performance

Gallery: 2021 Mercedes-AMG GLS 63: Pros And Cons

2021 Mercedes-AMG GLS 63

Engine Twin-Turbocharged 4.0-liter V8 w/Integrated Starter-Generator
Output 603 Horsepower / 627 Pound-Feet
Transmission 9-Speed Automatic
Drive Type All-Wheel Drive
Speed 0-60 MPH 4.1 Seconds
Maximum speed 174 MPH (electronically limited)
Efficiency 14 City / 18 Highway / 16 Combined
Weight 5,700 Pounds (est)
Seating Capacity 6
Cargo Volume 17.4 / 42.7 / 84.7 Cubic Feet
Base Price $132,100
As-Tested Price $153,035