At the dragstrip, the GL continued to astound. Posting the seventh-heaviest curb weight (5468 pounds) and the fifth-highest power rating (335 horsepower), the GL nevertheless delivered the third-quickest 0-to-60-mph sprint (6.5 seconds) and the quickest quarter-mile time (14.9 seconds at 93.0 mph), prompting the query: How'd this big boy get so quick? Peek under the hood, and the answer is evident--a powertrain as slick and refined as a Rolls-Royce turbofan. A member of Mercedes's all-new four-valve M273 engine family, replete with dual-overhead camshafts, two-stage magnesium intake manifold, and variable valve timing on intake and exhaust valves, the GL's all-aluminum 4.7-liter, 335-horse V-8, along with its seamless, seven-cog 7G-Tronic partner, distributes power smoothly and effortlessly via the full-time 4Matic all-wheel-drive system, delivering acceleration that's speedy and serene. Motor Trend exec editor Stone observes that "the throttle/tip-in/shift phasing of this powertrain is spot on, something that has in the past been a problem on certain Mercedes models."

As one of seven sport/utilities to actually hit 100 mph at the test track (in 17.3 seconds, it was also the quickest to triple digits), the GL is sneaky-fast, capable of getting you into trouble. More important, the GL further is capable of keeping you out of trouble, thanks to myriad standard safety features, including eight airbags, active front head restraints, seatbelt pretensioners, ABS with EBD and brake assist, and electronic stability and traction control.

Of course, the GL450 wouldn't be the complete player it is if not for its clever packaging. Although 14 of this year's 22 SUVs offered a third row, none was as roomy and comfortable as the GL's, which boasted 34.0 inches of legroom (nearly five more than in the Escalade), 50.5 inches of shoulder room (almost two more than in the Q7), and 38.5 inches of headroom, about an inch more than in the Navigator. Technical director Frank Markus says, "I could sit back here from L.A. to Detroit!" Hyperbole, perhaps, but the GL's third row is ideal not only for kids but also for six-foot-tall adults, all of whom will enjoy a standard fixed sunroof. That level of comfort carries over to the first and second rows, too, both of which coddle occupants with ample room that features real leather and wood trim (a $1500 option). As a Mercedes, the GL isn't short on options, allowing customers to tailor their vehicles appropriately. From a DVD-based navigation system and a harman/kardon digital surround-sound system to a rearview backup camera and a heated steering wheel, the GL offers goodies for all tastes and budgets.

For those who believe the GL's standard 7.9 inches of ground clearance and 19.3 inches of fording depth don't quite make it off-road-worthy, there's a $2200 Off Road Package--two locking differentials, front and rear underbody skidplates, and an adaptive damping system--that bumps those clearances up to 10.9 and 23.6 inches, respectively, enough room to allow the rock-crawling mechanicals to work their magic.

Want more variety? For those concerned about fuel mileage, a 45-state legal, Bluetec turbodiesel-powered version is right around the corner. It runs on the new low-sulfur diesel fuel and combines low-end torque with reduced emissions. Performance? It's not officially announced, but a 500-plus-horsepower AMG 63 version will enter the model mix some time soon, too.

Sure it's not cheap, but neither are well-equipped versions of the Audi Q7, GMC Yukon Denali, Lincoln Navigator, and Cadillac Escalade, the last burdened with a base price $1605 dearer than the GL's. Value? The GL's got it. In-class superiority? You bet, certainly considering the GL's ingenious interior packaging and stout performance numbers, most of which sit either atop or near the top of the field. As for marketplace significance, not only is the GL Mercedes's first full-size sport/utility, it's also its best ever. Add it up, and you'll know why we named the Mercedes-Benz GL450 Motor Trend's 2007 Sport/Utility of the Year.