AutoRide is an optional package that automatically varies shock damping according to driving conditions. Whether riding empty, carrying a full load of people, or towing a horse trailer, AutoRide continually adjusts the suspension for optimum ride and handling. This technology also helps reduce dive on braking (so that the nose of the vehicle doesn't dip down unduly) and body roll (lean) during cornering. AutoRide is standard on Denali, optional on 1500 and 2500.

The suspension system in the 1500 models soaked up the large potholes and rough terrain we encountered. The independent front suspension flattens the most rugged terrain so that the Yukon XL's passengers feel coddled, while the solid rear axle allows impressive towing capability. The suspension also contributes to the Yukon XL's impressive turning radius when compared with pre-2000 models, useful for crowded parking lots, U-turns, and off-road driving.

Autoride didn't seem to help our 2500 with Quadrasteer, however, which rode rough on I-405 in Los Angeles. Quadrasteer requires heavier components to sustain all of the extra equipment on the rear axle. Our 2500 also came with light-truck tires, rather than passenger-car tires. Weight would likely improve the ride, but we don't think we'd want to put up with the jounciness of the heavy-duty suspension on a daily basis unless we were towing heavy trailers.

Brakes were revised for 2003 and we found they worked very well. The new brakes are easy to modulate, offered good pedal feel, and seemed to do a good job of stopping our 2003 Yukon XL 2500. They are a far cry from pre-2000 GM truck brakes.

StabiliTrak is a valuable option that could save your life someday or reduce the chance of stuffing your big Yukon XL into the ditch. StabiliTrak is an anti-skid system that compares the driver's intended path with the vehicle's actual path, and adjusts engine torque and any of the four brakes to help bring the vehicle back under control. Sophisticated sensors monitor the suspension, steering, antilock braking and traction control systems, constantly measuring steering angle, wheel speeds, brake pressure, lateral and longitudinal acceleration and yaw rate (the vehicle rotation rate, such as when cornering).

Shifting among the four-wheel-drive modes is easily accomplished with four switches mounted on the left side of the instrument panel. The top switch engages GMC's automatic four-wheel-drive system, which automatically transfers power from the slipping wheel to the wheels with traction. A switch controls two-wheel drive, four-wheel drive and four-wheel drive low-range. This system makes shifting from two-wheel drive to four-wheel drive and back as easy as turning on the radio. By contrast, Denali's full-time all-wheel-drive system requires no input from the driver. And it's the best setup in inconsistent conditions (patches of snow and ice, gravel and pavement) because it transfers power to the wheels with the best traction.

Responsiveness from each of the three available V8 engines is excellent. Most people will find the standard 5.3-liter V8 a great companion. Our Yukon XL 2500 came with the big 6.0-liter, which felt and sounded powerful when accelerating onto the freeway.

All Yukon XL models come with a tow/haul mode for the transmission. Pressing a switch on the end of the gearshift lever changes the shift points of the automatic transmission. The tow/haul mode improves performance while towing through mountainous terrain and lessens wear on the transmission. It does this by holding it in any given gear longer and by shifting more abruptly to reduce heat buildup.

Towing a really heavy trailer? A 1500 model is plenty for pulling a car trailer or a light boat trailer, but you may want to look at the 2500 models if you have a heavy load to pull and you pull it often. The 1500 model comes with torsion bars up front and coil springs in the rear, which filter road vibration much better than the 2500 model, which is fitted with rear leaf springs.

Quadrasteer ($4495) provides vastly improved maneuverability at low speeds. By turning the rear wheels opposite the direction of the front wheels, this four-wheel-steering system reduces the curb-to-curb turning diameter of the Yukon XL 2500 from the standard 44.3 feet to 36.5 feet, an improvement of about 20 percent. That's a huge difference when maneuvering in crowded parking lots and public garages, and allows a U-turn in places that previously required backing up. Quadrasteer becomes even more important when towing trailers. It greatly improves control when backing, eliminating trial and error runs. It also allows you to move a trailer into spots where you could not physically do so without it.