Front driver and passenger airbags are standard equipment for all trim levels. Unlike some other trucks in the full-size class, the Sierra doesn't offer side-impact or curtain airbags. Disc brakes at all four wheels are standard on the Denali and 1500HD, but front discs and rear drums provide stopping power on other trim levels. All models feature four-wheel ABS, but stability and traction control don't make the options list. The optional OnStar system uses satellite and wireless technology to alert help in the event of an emergency and also offers concierge-type services--providing directions, making reservations, and so on--depending on the service package selected. New for 2005, OnStar gets an upgrade with better voice recognition ability and both digital and analog wireless coverage. An available hands-free mobile phone with voice dialing allows the driver to keep his eyes focused on the road.
The Sierra 1500 offers an unmatched number of powertrains--six, to be exact. A limited-production "mild hybrid" system debuted in 2004; other than using a beefed-up alternator, the system is essentially a conventional gasoline engine that automatically shuts off when the vehicle isn't moving, such as at a stoplight, and fires back up when its time to go. Fuel economy is claimed to rise by 10 percent, but when you're barely getting 16 mpg in the city, that's not much. The gain isn't worth the hassle of the engine shutting down at inopportune times--like when you're about to take off at a green light. The most legitimate use for this option is as a mobile power generator, as it provides four 120-volt outlets, but even then, for the money, a conventional generator is a more efficient way to achieve the same end. For now, the Sierra "hybrid" is available for fleet and commercial use, mostly on the West Coast. Rather than this hybrid solution, we'd prefer to see the heralded Displacement on Demand cylinder-deactivation system propagate through the GM powertrain ranks.
Other highlights of the powertrain lineup include a 6.0-liter V-8 in the 1500HD (300 hp) and the Denali (345 hp), and a 5.3-liter V-8 (295 to 310 hp), the top-spec engine for the light-duty trim levels. Both provide more than adequate power and torque. When properly equipped, the 1500HD has a tow rating of more than 10,000 pounds, making it one of the best in its class, although it has a pricetag to match its power. Unique to this segment, the Denali's torque is fed through full-time all-wheel-drive rather than traditional part-time four-wheel-drive. The full-time system can dynamically shift power from one axle to another, depending on which has more grip at a given time. A small-displacement 4.8-liter V-8 is offered with a still impressive 285 horsepower, though it concedes 40 lb-ft of torque to the 5.3L. The budget choice is the serviceable 4.3-liter/195-horse V-6, which provides only a minor advantage in fuel economy over the eight-cylinder powertrains'.
The Sierra's solid ride quality is impressive. At highway speeds, the chassis stays buttoned down, with limited float, feeling better connected than the Chevrolet Silverado. Steering response is equally good, and certainly better than that of some of the Sierra's competition. The downside to this relatively good body control is that the ride can be harsh over really rough pavement, especially with an empty bed. The Nissan Titan and Ford F-150, both significantly newer designs, manage to combine good body control with a more compliant ride. Torque is plentiful in the larger V-8s, but the four-speed's ratios are too widely spaced for rocket-grade acceleration. Many competitors have moved to five-speed automatics to put down the power better and help fuel economy, and we think the GMCs would benefit from the same change.