1999 GMC Sierra 3500 Review (continued)
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Driving Impressions

The Sierra SLT is kind of like a tall, long-wheelbase limousine. It's as quiet as a luxury car, supremely smooth, and well behaved, mostly because of the new chassis, which offers a 23-percent increase in stiffness, and the strong new cab design. New mounting and isolation hardware reduces noise and vibration, and there's a cast magnesium beam behind the instrument panel and a lateral steel beam to further reinforce the body. Squeaks and rattles have been virtually vanquished. This strong truck lets its suspension soak up all the road irregularities so well that its behavior is near-luxury. Its 133-inch wheelbase improves the ride further and enhances high-speed stability.

Sierra's four-spoke steering wheel connects to a new rack-and-pinion steering system that has a big dead spot on center, which GMC says is designed to minimize steering corrections. The steering feels a bit too light, but we found it tracks straight and handles well on pavement.

Our Sierra SLT test truck carried the 5.3-liter (324 cubic-inch) engine, rated at 270 horsepower and 315 foot-pounds of torque. This engine has a tall torque curve, which makes it useful for light towing and hauling, but it's also excellent for commuting and touring.

The Tow/Haul shift mode that comes as part of the optional towing package does a great job of keeping the automatic transmission in a lower gear, improving response and reducing wear on the transmission. Overall, we found the Sierra provides a stable platform for towing and the 5.3-liter engine had enough torque to pull a 3,800-pound trailer through the mountains.

Sierra's brakes have been greatly improved compared to the previous model. The four-wheel disc brakes are huge and powerful and come standard with ABS. Braking force comes into play only an inch into the pedal travel, a major improvement over the clunky pedal action on the previous C/K pickup. Dynamic Rear Proportioning improves stability under heavy braking whether the truck is loaded or empty. GMC promises huge improvements in fade resistance, pad life and heat dissipation, and after our desert test drive, we believe it.