Driving Impressions

On the road, the Sierra is quiet and well behaved, more so than other full-size pickups. It's stable at high speeds, particularly the longer wheelbase (143.5-inch) models. It rides well and handles well. The optional 5.3-liter V8 (327 cubic inches) delivers pleasurable performance around town and on the Interstate. Called the Vortec 5300 by GM, it's rated 295 horsepower and 335 pound-feet of torque, plenty for light towing and hauling. For 2005, an aluminum-block version of this engine produces 310 horsepower, but is available in Extended Cab, standard-box 4WD models only. The base V6 produces 195 horsepower and 260 pound-feet of torque, but most Sierra buyers opt for a V8 and automatic transmission. With 285 horsepower and 295 pound-feet, the 4.8-liter Vortec 4800 V8 is the most popular engine for this truck. With its 6.0-liter, 345-horsepower V8, the Denali really gets with the program. All of these Vortec small-block V8s are based on the SB-2 architecture introduced on the Corvette and extended to the Camaro and Firebird in 1999. Since 2003, they have featured Electronic Throttle Control for more precise, consistent throttle operation; new oxygen sensors offer improved reliability and reduced emissions during warm-up. All of GM's Vortec engines come with 100,000-mile platinum-tip spark plugs, sequential fuel injection, and 150,000-mile anti-freeze. A Tow/Haul mode helps the four-speed automatic transmission keep its cool when towing. Press the Tow/Haul button on the end of the shifter, and the transmission holds gears longer before shifting up or down, reducing the annoying tendency to hunt between third and fourth gears in hilly terrain. Shifts are harder and quicker in Tow mode, reducing heat buildup in the transmission. We find it improves the performance of the truck when pulling a trailer and reduces the driver's annoyance level. Two-wheel-drive 1500s have rack-and-pinion steering, but there is still a fairly wide dead spot in the center when cruising. GMC says this is intentional, to minimize steering corrections on the highway. The steering feels a bit light, but the truck tracks beautifully and handles well on pavement, loose dirt, deep dirt and even off-road. Recirculating-ball steering comes on four-wheel-drive, 2500HD, 3500 and Quadrasteer models. Quadrasteer makes driving these big pickups so much nicer in tight, crowded parking lots. Available on Extended Cab, standard-box models with 4WD; 1500HD Crew Cabs with 2WD or 4WD; and on 2500HD Crew Cabs; it reduces the turning circle by 10 feet on an Extended Cab standard-box model (from 47.3 to 37.4). We tried towing with a Quadrasteer-equipped truck, and it felt more stable, especially on winding roads, where it was easier to drive, and where the trailer tracked better behind it. If you tow frequently, you really owe it to yourself to test a truck with Quadrasteer. Backing a long trailer into a parking space at a 90 degree angle is much easier with Quadrasteer than without it. The system shortens turning circles with trailers and makes backing up more intuitive. Brakes are large, 13-inch discs up front with 11.65-inch drums in the rear; 1500HDs, Quadrasteer models and Denali have discs on all four corners. ABS is standard on all models. Dynamic Rear Proportioning (called Electronic Brake Distribution, or EBD, by other manufacturers) improves stability under heavy braking, whether the truck is loaded or empty, and can reduce stopping distances. Jam on the brakes, and most vehicles without ABS will lock up the rear tires, because most of the weight is being transferred to the front wheels. ABS keeps the rear wheels from locking, but you still lose braking effectiveness as most of the weight is transferred to the front tires. With Dynamic Rear Proportioning, brake pressure is transferred to the tires with the best grip, thereby reducing stopping distances. Two-wheel-drive models can be ordered with traction control ($225). Four w

Final Word

Sierra Denali delivers unique styling and sumptuous luxury, along with an exclusive high-performance V8 and full-time all-wheel drive. By upgrading Denali from an Extended Cab to a Crew Cab, GMC has made its flagship pickup more family friendly as well. All GMC Sierras deliver lots of power, big payload capacities, and plenty of towing capability. They look classy and distinctive, more upscale than the Chevy Silverado. The Sierra pickups are among the smoothest, quietest, most civilized, best equipped, and most enjoyable trucks we've driven. The GMC Sierra is a must-see if you're buying a new full-size pickup. New Car Test Drive editor Mitch McCullough is based in Los Angeles.