A new Sierra half-ton pickup truck based on the all-new GMT800 platform provides an important statement for the brand in 2000. Replacing the long-running previous generation truck, the new GMC Sierra 1500 featured revised engine power as well as an extended cab model with standard third door. The older Sierra truck body style remains in production as the Sierra Classic and is used with Sierra 2500 and 3500 variants. Buyers of the Sierra 2500 model now have the option of a Crew Cab version. The 1999 model year Sonoma employs a new AutoTrac four-wheel drive system providing automatic engagement of all wheels. 1999 also introduces a more polished example of the GMC Yukon sport utility vehicle. The luxury-themed GMC Yukon Denali stands out with exclusive exterior styling touches and is outfitted with a high-end leather interior.