The GLS 450 comes with a turbocharged V6 engine (362 hp, 369 lb-ft), 19-inch alloy wheels, a self-leveling air suspension, power-folding and auto-dimming side mirrors, LED running lights and taillights, roof rails, a power liftgate and Mbrace Connect remote vehicle access (via smartphone app; includes remote start).

Interior highlights include premium vinyl upholstery, heated front seats, a 10-way power driver seat (with four-way power lumbar adjustment), driver-seat memory settings, a power-adjustable leather-wrapped steering wheel, an auto-dimming rearview mirror, genuine wood trim and dual-zone automatic climate control. Technology highlights include the COMAND infotainment interface (with both a control knob and a touchpad), an 8-inch central display, a rearview camera, Bluetooth, a 115-volt household-style power outlet, and a sound system that features HD radio and dual USB ports.

An available Premium package adds keyless entry and ignition, a power front passenger seat with memory settings, lighted door sills and multicolor ambient lighting, a navigation system with real-time traffic, voice controls, Apple CarPlay and satellite radio, as well as lane keeping assist and blind-spot monitoring.

The Lighting package bundles adaptive LED headlights and automatic high beams. The Parking Assist package adds front and rear parking sensors, an automated parallel parking system and a surround-view camera system. Also available are three-zone automatic climate control, ventilated front seats, leather upholstery, a 13-speaker Harman Kardon sound system with a CD/DVD player, an SD card reader, and multicontour front seats that add a massaging feature and adjustable side bolsters and shoulder supports.

The GLS 550 starts with all of the above as standard, but it uses a twin-turbo V8 engine (449 hp, 516 lb-ft). It also adds 21-inch alloy wheels, adaptive suspension dampers, sporty exterior styling cues, soft-close doors and upgraded interior trim (including wood steering-wheel inserts). The optional Night package throws in 21-inch black wheels and gloss-black exterior accents.

Optional items on both the GLS 450 and GLS 550 include a panoramic sunroof, heated second-row seats, diamond-quilted leather upholstery and the Driver Assistance package, which adds adaptive cruise control, lane keeping assist, blind-spot monitoring, and front and rear collision mitigation. Also available is an Off-Road package that includes an upgraded multimode terrain selector, a dual-range transfer case and front underbody protection; on the GLS 450, it also adds the GLS 550's standard adaptive dampers.

The high-performance AMG GLS 63 starts with most of the above and adds an even more powerful turbocharged V8 (577 hp, 561 lb-ft), a sport exhaust, exclusive 21-inch alloy wheels, a sport-tuned suspension, upgraded brakes, adaptive stabilizer bars (the Active Curve System in Mercedes-speak), AMG-specific styling elements inside and out, enhanced bolstering for the front seats, upgraded leather upholstery and a flat-bottom sport steering wheel.

All three GL models can also be outfitted with a trailer hitch, a heated steering wheel, power-sliding second-row seats for improved third-row access, rear side-window sunshades, a rear entertainment system, a Wi-Fi hotspot and a 14-speaker Bang & Olufsen audio system.