The G's ride is generally composed on smooth surfaces, ready to rumble with tire noise when the texture turns to gravel, or worse. The amount of ultimate grip available is astonishing, and the G55 model can be hustled to its limits thanks to big, grippy 20-inch wheels and tires and upgraded six-piston brakes shared with the ML63. That is, until stability control intervenes--as it does quite often, and quite early, before the G Class' heavy doses of body roll trigger all sorts of red flags in the traction system, cutting engine power and engaging brakes to scrub off speed before it scrubs off tire tread. Or paint.
The appeal of the G-Class clearly rests in its extreme off-road talents. It looks heavy-duty-and it is--save for towing capacity, which is a distinctly European-sounding 3500 pounds, about what you'd get in a Ford Flex. An automatic four-wheel-drive system with three electronic locking differentials and low-range gearing keeps it clawing over rocky paths and plugging through muddy bogs where you'll only find Land Rover Defenders and Toyota Land Cruisers and other endangered species. The G has ground clearance of almost 8.3 inches, approach and departure angles of 36 and 27 degrees, and can ford almost two feet of water. It maintains its rugged character, in part, by dismissing the latest terrain-control systems adopted by many of its competitors. It's gone beyond the days of manually locking wheel hubs, what with its four-wheel traction control and hill-start assist, but not much more--not when compared to the electronically controlled driving modes of the latest Lexus LX 570 or Range Rovers.
Two G Class models are defined by their powertrains. The G550 sports Mercedes' widely used, smoothly stalwart 388-horsepower V-8 engine with 391 pound-feet of torque, coupled to a seven-speed automatic with a high degree of manual gear control. It's a well-sorted drivetrain, smooth in highway driving and docile until it's not. In the 5,600-pound G550, the normally aspirated V-8 and automatic combine for acceleration to 60 mph of 6.0 seconds; it'll reach a limited top speed of 130 mph, but it struggles to achieve a 12/15 mpg fuel economy rating.
The G55 AMG adds two turbochargers to the same engine for a net of 544 horsepower and 560 pound-feet of torque. It uses a paddle-shifted version of the seven-speed automatic to punch new barn-door holes in the atmosphere. The muscular, rorty engine pounces to 60 mph in just 5.3 seconds, despite a curb weight over 5,700 pounds. Top speed is reined in to 130 mph. Gas mileage hasn't been calculated yet for U.S. models, but the G63 AMG will have stop/start technology as standard equipment--which should improve on the former supercharged G55's abysmal 11/13-mpg EPA rating.
The G550, we've found, keeps a very brisk pace, but on-road performance in the G63 AMG is impressive and even shocking, within logical boundaries. To that end, the AMG's top-heavy feel requires attention on the highway, though steering takes less upper-body strength than in the past, thanks to new electric setup that's lighter than the old recirculating-ball setup. The steering system still doesn't offer much feedback, since it's up against an electric motor, live axles, four-wheel drive, and massive 18-inch or 20-inch tires--any one of them, krypton to natural wheel feel. The gas pedal requires a hefty foot too, and so do the brakes. In other words, no multitasking allowed.