The 2018 GLS class has three powertrain configurations and all of them deliver power to all four wheels. Unfortunately for this year, the diesel powertrain option has been phased out of the US market. The base GLS 450 is powered by a 3.0 liter turbocharged V6 producing 362 horsepower and 369 lb. ft. of torque, mated to a nine-speed automatic transmission. Next is the GLS 550 that is powered by 4.7 liter turbocharged V8 producing 449 horsepower and 516 lb. ft. of torque, mated to a nine-speed automatic transmission. The top-of-the-line AMG GLS 63 is powered by a 5.5 liter turbocharged V8 producing 577 horsepower and 561 lb. ft. of torque, mated to seven-speed automatic transmission. Even with the base V6 engine and the massive body, there is no lack of oomph and acceleration is far from sluggish. The GLS took 5.7 seconds to reach 60 mph from a standstill, more than good enough in the full-size SUV segment. The four-wheel drive definitely helped in putting the power to the ground and the transmission performed smoothly. Handling through the turn depends on how fast it attacks the corner. Body roll is evident in spirited driving despite stiffening up the suspension settings. In more reasonable speeds however, the stability is there and retains composure. The steering is accurate but the responsiveness is muted down. Despite being a common steering trait among bigger SUVs, it wasn’t as vague as its competition. With its massive body, the brakes took the GLS to a halt from 60 mph in 120 feet, a figure more comparable to a smaller SUV. The bite from the brakes isn’t as immediate however, but resulted to less nosedive. The feel of the pedal started off as soft but firms up through the pressing motion.
The base GLS 450 trim comes standard with an adaptive air suspension, power-folding and auto-dimming side mirrors, LED running lights and taillights, power liftgate, power-adjustable driver seat, driver seat memory settings, automatic climate control, ventilated front seats, multi-contour front seats with massage, power-adjustable steering wheel, auto-dimming rearview mirror, automatic climate control, Bluetooth, HD radio, 115V power outlet, two USB ports, SD card reader and an infotainment system with 8-inch display, touchpad, control knob, CD player and a 13-speaker Harman Kardon sound system. The Premium 1 package includes keyless entry and ignition, power-adjustable front passenger seat with memory settings, voice commands, navigation, satellite radio, Apple CarPlay, Android Auto, and a couple of advanced safety and driver aids. The Lighting Package adds active LED headlights and adaptive high beam assist. The Driver Assistance and Parking Assist packages include several advanced safety and driver aids. The GLS 550 trim builds on the previous trim and now comes with upgraded performance parts and upscale exterior and interior appointments. Optional for both the GLS 450/550 are a power sunroof, heated second row seats and the Off-Road package that equips them with performance and exterior parts for off-road use. The top-of-the-line AMG GLS 63 trim comes with all the bells and whistles that also include performance parts upgrades courtesy of AMG and has its own interior and exterior parts. Stand-alone options that can be added to any model include a sunroof, trailer hitch, ergonomic heated steering wheels, power-sliding seats, rear-seat entertainment system, Wi-Fi hotspot and a 14-speaker Bang & Olufsen sound system.
The 2018 model has not undergone crash testing by the NHTSA nor the IIHS. Standard advanced safety and driver aids include a rearview camera, active brake assist, driver attention assist, crosswind assist and adaptive high beam assist. Advanced safety and driver aids that are available through packages include forward collision warning, blind-spot monitoring, lane departure warning and intervention, adaptive cruise control, automated steering, collision avoidance, automated parking, 360-degree camera and front and rear parking sensors. Mercedes Benz’s mBrace telematics system offer remote access to the vehicle by connecting a smartphone and being able to control the doors, ignition, horn and lights. Other services include Roadside Assistance Connection, Vehicle Finder, Speed Alert, and Valet Protect.
The 2018 model measures 201.6 inches in length, 76.14 inches in width, 72.7 inches in height, and with a wheelbase of 121.1 inches. For this year, no changes have been to the exterior from last year’s model. For all three trims, they all have a different front bumper with variations in the design of the vents. Their wheels also vary in design and diameter, starting from 19 inches all the way up to 21 inches. The midrange and high end trim have side skirts, a lip spoiler and wider rear bumpers for a sportier look. Roof rails come standard for all trims. The Appearance Package for the GLS 450 trim offer illuminated running boards and bigger 20-inch wheels. The Night Package for the GLS 550 trim offers bigger 21-inch wheels and exterior accents in a gloss black finish.
Getting inside didn’t require much of a stretch for the legs and the optional running boards were helpful. The passenger doors open wide for a trouble-free entry inside the spacious cabin. Legroom and headroom for all three rows of seats is generous, even the third row where there’s a good gap between the knees and the seat in front. With the three rows of seats, up to seven people can fit comfortably inside the cabin. The leather quality for the upholstery is supple to the touch and fit and finish is very clean and coordinated. Seat comfort is as expected for the German brand’s SUV offerings, providing all-day comfort that didn’t induce fatigue to the legs. As a luxury vehicle, the ride quality is plush on smooth pavement and controlled when going over road bumps. The suspension absorbed the impact without a problem and comfort is still achievable even on the sportier driving modes. Noise isn’t prevalent inside the cabin, therefore retaining the serene and luxurious ambience.
Behind the third row of seats is 16 cu. ft. of space, while there is 49.4 cu. ft. behind the second row of seats. Space then expands to almost 94 cu. ft. when both the second and third rows are folded down.