The GS450h is the first-ever hybrid gas-electric version of Lexus' mid-size sport sedan. It is designed to deliver high-performance as well as reasonably high efficiency. A Lexus Hybrid Drive powertrain combines a 3.5-liter V-6 engine with a compact, permanent magnet electric motor and 288-volt DC Nickel Metal Hydride (Ni-MH) battery pack, all driving the rear wheels. The hybrid powertrain collectively produces 340 horsepower and can accelerate the GS 450h from zero to 60 mph in just 5.2 seconds -- better performance than the gas-only GS430 V-8 but with better fuel economy and lower emissions. Preliminary figures peg the GS450h as being capable of returning 25 mpg city/28 mpg highway -- and 26 mpg in "combined" driving. The GS 450h is certified as a Super-Low Emissions Vehicle (SULEV) and is a "full hybrid" capable of operating in purely electric mode to conserve fuel and lower emissions. The hybrid GS comes loaded with features, including Toyota's Adaptive Variable Suspension (AVS), standard 18x 8-inch aluminum alloy wheels and 245/40R18 Z-rated summer performance tires; all-season run-flat tires (in the same size) are available, as is an Active Stabilizer system that uses an Electronic Control Unit (ECU) to calculate the force needed to counter excess body sway during hard cornering.