2021 Mercedes-AMG GLS 63 Road Test and Review

2021 Mercedes AMG GLS 63 Green Front Three Quarter ・ Photo by Mercedes-Benz

You can no longer call it a trend or a fad. High-performance luxury SUVs are no flash in the pan. They’re here to stay and they just keep getting more powerful. Take this new 2021 Mercedes-AMG GLS 63. It isn’t only the most powerful SUV Mercedes has ever cooked up, with 603 horsepower it’s also the most powerful seven-passenger SUV on the market.

Mercedes’ in-house performance division has been increasing the performance of the brand’s SUVs for over 20 years. In fact, AMG invented the breed back in 1999 when it introduced the ML55, the fastest sport utility the world had ever seen up to that time. Some purists scoffed, but today half of all AMGs sold are SUVs and most luxury brands offer at least one high-performance sport-utility, including BMW, Porsche, Bentley, Lamborghini, Land Rover, and Maserati. Some, like AMG, offer several models — and the GLS 63 S is its largest and most powerful.

Prices Start at $133,095

Like its main rival — BMW’s M division, which is known for cars like the M3 and M5 — AMG is Mercedes’ in-house tuner or hot-rod shop. Since the 1970s, its engineers have been rejiggering standard Mercedes models into some of the fastest cars and SUVs on the road, adding sport-tuned suspensions, bigger brakes, and, of course, more horsepower.

Its products are tuned on the world’s racetracks, including the legendary north loop of Germany’s Nurburgring, a circuit universally considered the most challenging and most dangerous in the world. It’s there, under extreme high-speed conditions, that a special team of engineers has turned the Mercedes-Benz GLS into this high-performance luxury suv. Its base price is $133,095, including a $995 destination charge, which is very competitive for this small class. Most of AMG’s competitors don’t offer a third-row seat, including the BMW X5 M, Land Rover Range Rover Sport SVR, and Lamborghini Urus. Only the Bentley Bentayga offers similar horsepower as the GLS 63 along with an extra set of seats. But it costs far more. With options, our test vehicle cost over $150,000, but that's only approaching the Bentley’s base price.

Photo by Mercedes-Benz

It’s Built in Alabama

Like other GLS models, the new 2021 Mercedes-AMG GLS 63 is built in America, although its twin-turbocharged 4.0-liter V8 engine is hand-assembled in Germany before making its way to Mercedes’ factory in Tuscaloosa, Alabama. The engine is also used in the brand’s GT supercars, where it makes as much as 630 horsepower.

Here, the 4.0-liter twin-turbo V8 is rated at 603 horsepower and 627 lb-ft of torque. A nine-speed automatic transmission, all-wheel drive, and 21-inch wheels and tires are also standard. The SUV shares this hardware — along with its sport-tuned air suspension and high-tech interior — with the five-passenger 2021 Mercedes-AMG GLE63 S, which is also assembled in "the Heart of Dixie." The two SUVs look alike as well. AMG adds its signature grille with vertical louvers to both, along with a more aggressive front bumper with massive black air intakes, a rear diffuser, and a pair of enormous rectangular exhaust pipes on each side. It also flares their wheel arches to cover its huge wheels and tires and intensify the muscularity of their stance.

Photo by Mercedes-Benz

Powerful, Fast, and Refined

When you consider this SUV weighs well over 5,700 lbs, its acceleration is astonishing. Use its launch control feature, which unleashes the SUV at 2,800 rpm, and the GLS 63 rockets off the line — planting you back in the seat and holding you there as its nine-speed automatic snatches quick upshifts at 7,000 rpm. Mercedes says it hits 60 mph in just 4.1 seconds and its top speed is electronically limited to 174 mph. That’s nearly a half a second slower than the GLE 63 S, which is considerably smaller and lighter.

This is the first AMG V8 to get the company’s 48-volt EQ Boost system, a small electric motor mounted between the engine and the transmission. AMG calls it an integrated starter generator, and it applies its power momentarily to increase response, improve fuel economy, and smooth out the drivetrain. The result is an extremely refined driving experience with silky gearchanges and a start/stop feature that’s so smooth it’s almost imperceptible.

Photo by Mercedes-Benz

Responsive Performance Around Town

This is also the first SUV from AMG with liquid-filled active engine mounts, a technology also used by Porsche in its Cayman and Boxster sports cars. When you’re just cruising, they remain loose to keep things comfortable and isolate engine vibration. But toss the big SUV into a corner or get aggressive with its accelerator and they stiffen automatically to increase response and driver feedback.

With so much torque at low engine rpm, turbo lag is never a problem. Throttle response is quick and there’s supercar levels of passing power on the highway. The AMG’s nine-speed automatic transmission is alert, changing gears quickly and cleanly and always ready with a downshift. It also has a manual mode, and there are aluminum paddle shifters on the steering wheel for manual gear selection. The engine matches revs perfectly when you ask for a downshift.

Photo by Mercedes-Benz

Adjustable Suspension With Six Drive Modes

The GLS 63 offers six driving modes, including Sport, Sport+, Sand, and Trail. Each modifies the tuning and response of its engine, transmission, steering, and suspension. In Sport and Sport+, its suspension firms up to improve the SUV’s handling, while its suspension rises about 2.2 inches in Trail and Sand modes to improve ground clearance.

In every driving mode, the GLE feels solid and is one of the smoothest-riding SUVs in this class on the standard 21-inch wheels. Even in Sport+ mode, despite its huge wheels and tires, the GLS 63 soaks up most roads beautifully, and in Comfort mode, it rides with amazing compliance. However, pay up for the optional 22-inch or 23-inch wheel and tires and you’ll sacrifice some ride quality. This is unfortunate, as the available 23-inch matte black Monoblock wheels that cost an extra $4,950 are the best looking of the bunch. They make a serious statement.

Photo by Mercedes-Benz

Sports Sedan Handling

Despite its comfortable ride, the 2021 AMG GLE 63 S never feels floaty or disconnected from the road. It’s always planted and stable, which is especially impressive at high speeds.

AMG has also fitted the GLE 63 S with its new electrically operated Active Ride Control system that eliminates body roll. The result is an SUV that never feels tipsy despite its height and weight, one that’s easy to drive fast and offers incredible amounts of grip. Its handling is extremely predictable. It excels in fast wide-open corners, soaking up bumps and undulations without getting skittish or feeling nervous. And in tighter twists and turns, it understeers mildly if you start entering turns with too much speed, so you know its time to back off.

Photo by Mercedes-Benz

Family-Friendly Interior

Inside, the cabin is mostly standard GLS, so it’s beautifully appointed, impeccably assembled, and packed with high-tech features. AMG adds a fat three-spoke steering wheel with aluminum paddle shifters, heated and ventilated sports seats that are comfortable on long drives, and a soft Nappa leather. Wood or carbon fiber trims are available.

Rear seat space is generous. Five adults fit comfortably in the GLS, and the third row offers plenty of room for kids. Surprisingly, second-row captains chairs aren’t available. There are also nine USB ports throughout the cabin, and Mercedes offers Executive Rear Seat Packages that includes a 7-inch tablet and heated, ventilated, and adjustable rear seats. Storage is also plentiful and well thought out. There’s a large center console bin, big door pockets with slots for water bottles, and other cubbies for wallets and phones.

Photo by Mercedes-Benz

Massive Amounts of Cargo Space

The 2021 Mercedes GLS is Mercedes’ largest SUV. Like the other GLS models, the AMG GLS 63 offers a ton of cargo space. There’s 17.4 cubic feet behind its third row, which folds easily and is split 50/50. Behind the second row, which is split 40/20/40, there’s over 40 cubic feet of space. That’s plenty for most families, but there are larger full-size luxury suvs out there with more, like the Cadillac Escalade and Lincoln Navigator.

With all of its rear seats folded out of the way, there’s 84.7 cubic feet of space. Every Mercedes GLS 63 comes with a power liftgate, and the liftover height is low, which makes loading easier. However, we still prefer the unique clamshell tailgate design of the BMW X5 and the Land Rover Range Rover. It gives you a place to sit at tailgate parties.

Photo by Mercedes-Benz

Final Thoughts

The new 2021 Mercedes GLS 63 is also one of the safest SUVs out there. Mercedes offers a long list of high-tech safety systems on the SUV. Blind-spot monitoring, adaptive cruise control, active brake assist, and Mercedes’ Pre Safe system are standard. Mercedes also includes Active Steering Assist, which helps keep you in your lane. Unfortunately, it intervenes too abruptly, yanking the SUV away from the road lines. Although the GLS hasn’t been crash-tested yet by the National Highway Traffic Safety Administration or the Insurance Institute for Highway Safety, NHTSA has given the GLE a five-star rating, and it has received a Top Safety Pick+ rating from IIHS, its highest honor. We have no reason to believe the GLS would perform differently than its platform twin.

Overall, the 2021 Mercedes-AMG GLS 63 is comfortable, handsome, and family-friendly, and its performance is inspired. Few SUVs are this fun to drive. If you’re in the market for high-performance SUV that seats seven, it’s an excellent choice.

Photo by Mercedes-Benz