Following on from the news that Mercedes-AMG is launching the mighty GLE 63 and GLE 63 S models, here's another stonkingly quick, big SUV from the same house: it's the AMG take on the third-generation version of the seven-seat GLS SUV. Because this mighty behemoth, is, well, a mighty behemoth, the Mercedes-AMG GLS 63 4Matic+ only gets the 612hp + 22hp V8 and EQ Boost drivetrain that is seen in the GLE 63 S. This delivers the same peaks of 634hp and 850Nm, enough to see the mahoosive wagon hit 62mph from rest in just 4.2 seconds, on its way to a 155mph limited maximum (174mph with the optional AMG Driver's Package). Fuel economy is in the order of 23.7mpg, if you're careful, coupled to 273g/km of CO₂ emissions, and the same AMG goodness has been poured into the biggest Stuttgart SUV's chassis: so there's AMG Active Ride Control air suspension with 48-volt anti-roll stabilisation and adaptive dampers, there's 4Matic+ with an electronically controlled limited-slip differential, there's a nine-speed AMG Speedshift TCT torque-converter auto, there are gigantic brakes (400 x 38mm front discs gripped by six-piston, grey-painted fixed callipers at the front, 370 x 32mm rear discs with a single-piston floating calliper at the rear) and there's AMG-tuned speed-sensitive steering. Outside, the vertical-vaned radiator grille, twin-powerdome-straked bonnet, gaping lower front air intake, wider wheel arches housing 21-inch (up to 23s available) alloy wheels and quad exhausts at the rear mark it out as more than a GLS 350 d, while inside there's the full MBUX infotainment on the Widescreen Cockpit display, plus all the luxuries you'd expect of this German seven-seat SUV - only with an AMG flavour for the seats, steering wheel and trim finishers.