The performance-tuning geniuses at Mercedes-AMG have finally been let loose on the new GLS-class SUV, and from those solid bones they've created the 2021 GLS63. Powered by a fire-breathing 603-hp twin-turbo V-8, luxuriously appointed, and spacious it offers commodious accommodations for the family that wants to travel rapidly—really, really rapidly. Mercedes-AMG has thrown all the tech features it has at the GLS63, including dual 12.3-inch infotainment displays, an available semi-autonomous driving mode, and a 48-volt hybrid system to help the big SUV's performance. What brand of performance is that? The kind that enables it to accelerate like a rocket, V-8 engine roaring. This beast is a heads-up competitor to other oversized hot-rods such as the BMW X7 M50i and the Range Rover SV Autobiography—and comes with a price tag to match.
What's New for 2021?
The GLS63 is all new for 2021, arriving after a brief pause when the previous generation ended production after the 2019 model year.
Pricing and Which One to Buy
- GLS63 4Matic: $133,095
Although the GLS63's starting price is deep into the six-figure realm, we'd still suggest a few options sure to please the whole family. For one thing, the Warmth and Comfort package is a nice bundle for those in northern climates, as it adds heated door panels, heated armrests, and a heated center console. We'd also suggest the Energizing package which includes the in-cabin fragrance diffuser and the Acoustic Comfort package, and also adds increased cabin insulation for a quieter interior. Mercedes-AMG also offers a host of standalone features that may catch your eye, including the bonkers 23-inch multi-spoke forged wheels that look just perfect when framed within the GLS63's muscular wheel wells.
Engine, Transmission, and Performance
Under the hood of the GLS63 is a twin-turbocharged 4.0-liter V-8 engine that makes a whopping 603 horsepower with the help of a 48-volt hybrid system. All-wheel drive is standard, as is a nine-speed automatic transmission and air suspension. We were blown away by the 2021 GLS63's performance at our test track as it out-accelerated several hot sports cars we've tested recently, tearing off a blistering 3.6-second zero-to-60-mph run. For comparison, the old GLS63—which made a mere 577 horsepower—managed a none-too-shabby 4.3-second zero-to-60-mph run. As impressed as we were with the GLS's acceleration, we can't say the same for its driving dynamics. The ride is firm, especially on the optional 23-inch wheels, but that firmness doesn't translate to a feeling of precision when cornering. The GLS's body bobs across road undulations more than expected, though it still offers plenty of grip to have some fun with on a twisty road.
Fuel Economy and Real-World MPG
The EPA hasn't released any fuel-economy estimates for the 2021 GLS63, but with an engine that powerful, we aren't holding out hope for economy-car efficiency ratings. On our 200-mile highway fuel-economy test route the GLS63 delivered a decent 22 mpg; the GLS63's main rival—the BMW X7 M50i—managed 24 mpg in the same test.
Interior, Comfort, and Cargo
Three rows of seating and interior styling that's slightly sportier versus the Benz-branded GLS-class sets the GLS63 apart from two-row SUV powerhouses such as the BMW X5 M and the Audi RS Q8. Like those competitors, the GLS63 is gorgeously appointed inside. Soft leather covers nearly every square inch of the cabin, and those areas that aren't leather-wrapped are treated to genuine wood trim and tastefully applied chrome; buttons and knobs are rendered in a rich-looking metallic finish. Front-seat occupants can enjoy a massage while blasting down the Interstate, and passenger space is generous in the second row, which can also be equipped with heated seats and power sunshades. The third row of seats is tight for adults but perfectly suitable for children. Cargo space is the same as the standard GLS-class, which in our testing fit four carry-on suitcases behind its third row and 30 in total behind the front seats.
Infotainment and Connectivity
The GLS63 comes standard with the same dual-screen infotainment setup found in the non-AMG variant. Two 12.3-inch screens, nestled next to each other in a shared bezel, form the digital gauge display and center infotainment display. Mercedes-Benz's new MBUX interface can be controlled via voice, touchscreen, or with the clickwheel mounted on the center console. Apple CarPlay and Android Auto integration is standard, as is a 4G LTE Wi-Fi hotspot.
Safety and Driver-Assistance Features
The National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS) have not released crash-test results for the 2021 GLS-class. Mercedes-AMG offers several driver-assistance features as standard, with more advanced features including a semi-autonomous driving mode. Key safety features include:
- Standard automated emergency braking with pedestrian detection
- Standard lane-departure warning with lane-keeping assist
- Available adaptive cruise control with semi-autonomous driving mode
Warranty and Maintenance Coverage
- Limited warranty covers 4 years or 50,000 miles
- Powertrain warranty covers 4 years or 50,000 miles
- No complimentary scheduled maintenance