The big news for GMC is the all-new Sierra full-size pickup truck, which is part of General Motors' first major redesign of its trucks in 10 years.

The 1999 Sierra offers three new higher powered, more efficient and cleaner

Vortec engines. Each features a longer, flatter torque curve for improved towing and hauling power. The base V-6 engine carries over, but the new Vortec V-8s include the 4.8 rated at 255 horsepower (hp) and 285 pound-feet (lb-ft) of torque; the 5.3 rated at 270 hp and 315 lb-ft of torque; and the 6.0, available in 2500 Series models, with 300 hp and 355 lb-ft of torque.

Automatic transmissions include a new "Tow/Haul" shift mode as part of a premier optional towing package to improve performance on heavily loaded Sierras or those pulling a trailer; it lengthens the time between gear shifts. A new active AutoTrac transfer case, available on four-wheel-drive Sierras, immediately and automatically provides traction where it is needed. There are roomier cabs on both regular and extended cab models and increased cargo room in the rear; a third door is standard on all extended cab models. There is a wider track for added stability.

The remainder of the lineup gets minor changes. The Yukon gets some new colors and the more upscale Yukon Denali gets new colors and some minor new features. Suburban gets new colors.

The Envoy gets an AutoTrac two-speed active transfer case that allows drivers to select between full-time all-wheel drive or shift-on-the-fly four-wheel drive for added traction and the Tow-Haul mode that provides smoother transmission performance when the vehicle is heavily loaded or towing a trailer.

The Jimmy also gets the AutoTrac two-speed active transfer case and the Tow-Haul mode. Sonoma four-wheel-drive models have a new Auto-Trac two-speed active transfer case. Safari gets new exterior cladding and new colors. Four-wheel-drive models get a new AutoTrac transfer case. The Savana gets some automatic transmission enhancements.

Here is the picture for OnStar. A dealer installed option, OnStar combines satellite technology and a cellular telephone to link drivers with a 24-hour service center, which can provide emergency help and other travel services. The Suburban is added to the list of GMC vehicles that get OnStar for 1999, joining the Denali, Yukon Denali and Envoy. The older generation of Sierra pickup trucks has OnStar. Those are the 3/4-ton, more than 8,600 GVWR (gross vehicle weight rating) and all 1-ton models. The new generation Sierra does not get OnStar. Those are the new ½- ton 1500 Series and 2500 Series below 8,600 GVWR models.