All new this year, the 1999 GMC Sierra gains unique styling to set it apart from its Chevrolet counterpart. The three-door cab configuration has been lengthened 4 inches providing more rear leg room. To go along with the styling are new engines which are more powerful and have better economy than last year. The Corvette LS1 derived 4.8-liter 255-hp V8 or 5.3-liter 270-hp V8 are paired with a 4-speed automatic transmission and an optional Z71 4-wheel drive system, which combine to offer a towing capacity of up to 8000-lbs. Mileage estimates are 16/21 mpg city/hwy. Standard dual front airbags, ABS, OnStar and optional leather seating make this Professional Grade GMC even more competitive with Ford F-150 and Dodge Ram 1500.