Piloting the redesigned 2013 Mercedes-Benz GL450 feels like driving a massive bank vault 鈥?solid, quiet and heavy. And if you鈥檙e not careful with the option sheet, you鈥檒l need your own bank vault to pay for it. Certain vehicles are made with specific markets in mind. The Mercedes-Benz GL-Class is one of them 鈥?an expensive luxury SUV designed for the American market, built in Alabama and aimed at wealthy Americans鈥?love for big, fancy trucks. Larger than international luxury SUVs like the Land Rover Range Rover but smaller than domestic models like the Cadillac Escalade, the GL-Class has been a hit for Mercedes-Benz both in the U.S. AMG trim. It鈥檚 the big papa of the Mercedes-Benz SUV lineup, slotting above the midsize ML-Class, which itself sits above the compact GLK-Class. The fourth SUV in the Benz lineup is the G-Class 鈥?a limited-production, ultra-expensive retro-wagon that is essentially a German Hummer. We recently tested the new third-generation 2013 Mercedes-Benz GL450 4Matic, a midlevel V-8-powered version, to see if this truly is the market鈥檚 best big SUV.

We also drove the high-performance GL63 AMG, which you can compare with the rest of the lineup here. To compare the new GL-Class with the previous-generation 2012 model, click here. Family-haulers come in many shapes, styles and prices in the U.S., with the GL-Class ranking near the top of the SUV food chain. A choice of powertrains is available, ranging from a surprisingly efficient (yet torquey) Bluetec diesel V-6 in the GL350 to a hugely powerful twin-turbo 5.5-liter V-8 in the top-of-the line AMG version. Our GL450 was the middleweight contender, powered by a twin-turbo 4.7-liter V-8 making a respectable 362 horsepower and 406 pounds-feet of torque. The diesel engine comes in the least expensive model 鈥?rare in any vehicle class 鈥?and delivers the best EPA-estimated fuel economy in the lineup at 19/26 mpg city/highway. The numbers fall to 14/19 for the turbo V-8 in the GL450, 13/18 for the GL550 and 13/17 for the GL63.

Our GL450 tester had plenty of power for acceleration, passing and cruising, while the GL63鈥檚 ferocious acceleration is far more than you鈥檒l ever need. Both SUVs required a heavy foot in order to tap into it, however. With either drivetrain, throttle response and transmission kickdown was unacceptably slow: Decelerate at an intersection, make a right turn and push the gas to accelerate again, and nothing happens for a measurable second. So you push further into the gas, and suddenly the truck kicks down and leaps forward, snapping everyone鈥檚 head back. Perhaps this is a trick Mercedes-Benz is trying in order to encourage slower driving and higher fuel economy, but it results in some frustrating dynamics in around-town use. A selectable Sport mode in the GL63 hastens accelerator response to quell some of the lag, which is worst in the drivetrain鈥檚 Comfort mode. That really is our only complaint about the driving experience, however, as the rest of the GL450鈥檚 behavior is quite civilized.

The electrically boosted power steering is direct and well-damped over broken pavement, but doesn鈥檛 inspire athletic driving. The brakes are more than up to the task of stopping this 5,401-pound beast without fade, with a firm, progressive pedal and confident control. Previous sampling of both the GL350 diesel and GL550 V-8 reveal them to be equally civilized machines, at home on high-speed cross-country treks as well as low-speed crosstown errands. Highway stability is commendable even in strong crosswinds, and the all-wheel drive is surefooted in slippery, icy conditions. Aside from the throttle and transmission interaction, driving the GL450 is a serene, luxurious experience. Among its myriad upgrades, the GL63 AMG gets unique steering tuning and active stabilizer bars atop an adaptive suspension that鈥檚 optional on lesser GL-Class models. For such an elaborate setup, the results underwhelm. On bumpy roads, the chassis quivers about; broken pavement induces hints of floaty, disconnected wheel-hop 鈥?a degree of clumsiness that鈥檚 unbecoming of a six-figure performance SUV. The GL63 boasts generous ride comfort, even in the sportiest of the suspension鈥檚 three settings.