Substantial size inside and out, combined with a quiet, smooth, and luxurious ride — that's the attraction of GMC's full-size SUV. The downside is its mammoth appetite for gas. The SLT gets only 15 mpg (city) and 21 (highway). But the vehicle does, at least, tip its hat to being green. Besides gas, the SLT uses E85, a fuel made from a mixture of ethanol and gasoline.

Outside, the ample grille, slick, smooth body, sweeping windshield, and large rounded-rectangular headlights give the Yukon a regal stance. Our tester came in a striking deep-blue metallic color and rode on 20-in. polished aluminum wheels (17 in. are standard). A neat feature is the hydraulic mechanism that automatically holds the hood up as soon as you open it. This is a lot easier than propping the hood up with a rod. My buddy was impressed with how easy the engine would be to work on. The alternator sits high and belts are accessible. Surprisingly, the engine looks small and only takes up about the middle third of the compartment.

The vehicle's interior is spacious. There is plenty of room for such necessities as boxes of DVDs, picnic coolers, tennis racquets, fishing poles, hiking boots, skateboards, and golf clubs. A DVD player in the ceiling is convenient for occupying kids on long trips. Two sets of wireless headphones let passengers watch movies without disturbing the driver.

Front, second, and third-row leather seats comfortably hold seven adults. For more cargo room, the third row folds down or you can remove it entirely. However, the seats are quite heavy and difficult to reinstall. The driver's seat, with optional 12-way power, comfortably positions my 5-ft 4-in. frame in front of the uncluttered instrument panel. The center stack includes an XM satellite radio, which sends out commercial-free music through a Bose premium speaker system. I especially liked that I could prop my right arm on the center console while driving.

The 320-hp Vortec 5.3-liter V8, which mates to a four-speed automatic transmission, delivers enough power to make the SLT sometimes seem like an oversized sports car. The coilover-shock front and multilink rear suspension deliver a smooth, tight, comfortably stiff ride, even on potholed dirt roads. Power-assisted rack-and-pinion steering provides responsive control, and efficient braking is ensured with four-wheel disc antilock brakes. Safety features are impressive, with OnStar service, a tire-pressure monitor, and head curtains and side air bags for all seating rows.

Standard, the SLT-2 is around $38,365. Options such as $2,145 for the navigation system, $1,795 for the 20-in. wheels, and $350 for a power liftgate took the sticker to over $50,000.