Chevrolet has added some additions to their SS performance line-up for 2009. The new HHR SS and Cobalt SS sedan are powered by a turbocharged 260-horsepower engine. Rejoining the Chevrolet Corvette after a 14-year absence, the high-performance ZR-1 name is attached to the most powerful production version of the sports car yet. The 638-horsepower Corvette ZR-1 leads Chevrolet's halo sports car line-up that also adds a standard power hatch pull-down for 2009. Greater performance is also extended to the Chevrolet Colorado with the addition of a 5.3-liter V-8 engine. Aside from emphasizing performance prowess in 2009, Chevrolet's Malibu Hybrid results in a 4-mile per gallon fuel economy improvement over the conventional four-cylinder sedan model. Officially replacing their truck-based TrailBlazer sport utility vehicle as well as Chevrolet's Uplander minivan, the Traverse is a large crossover vehicle. Capable of moving up to eight passengers, the Chevrolet Traverse is propelled by a powerful, high-feature V-6 engine. A six-speed automatic transmission is now standard on most eight-cylinder powered versions of the Chevrolet Silverado, Suburban and Tahoe models. The two-mode hybrid transmission has been added to the Suburban for 2009. Several Chevrolet models such as the Malibu and Silverado will provide motorists with added high-tech functionality of OnStar 8.0 suite.