A welcomed addition to Lexus’ entry-luxury sedan lineup, the HS 250h fits nicely between the IS luxury sport sedan and the ES luxury sedan. Research has shown that more than 60 percent of entry-luxury car buyers would have considered a hybrid if available, and the HS will provide these consumers with a viable purchase option.

Equipped with Lexus’ first four-cylinder gas engine, the 2.4-liter Atkinson-cycle powerplant is part of the latest Lexus Hybrid Drive System, which generates 187 total system horsepower. The highly efficient Atkinson-cycle engine, made possible by the Variable Valve Timing with intelligence (VVT-i) system, allows the expansion/power stroke to be longer than the compression stroke so that combustion energy can be more effectively used for production of engine power. The HS 250h sedan’s expected fuel efficiency will be more than 30-percent better than the most fuel-efficient model currently in the Lexus lineup, while earning a SULEV emissions rating utilizing regular 87-octane gasoline. Among the technologies adopted in the 2.4-liter four-cylinder engine are cooling piston oil jets; an optimized balance shaft rate for improved Noise, Vibration and Harshness (NVH) characteristics; and a hot-air venting system mounted behind the radiator.

Like the all-new 2010 RX 450h hybrid utility vehicle that made its debut in November, the HS 250h will include a new system designed to improve efficiency. The exhaust heat recovery system reduces engine warm-up time, thus allowing it to stop earlier, more often, and for longer periods. A windshield with infrared-ray (IR) reduction properties, which helps keep the interior more cool, has been adopted in order to decrease the amount of air conditioning needed to lower the cabin temperature. In addition to the exhaust heat recovery system and the IR windshield, available power-saving LED headlamps also contribute to improved fuel efficiency and emissions.

The all-new HS 250h sedan’s 0.27 drag coefficient (Cd) makes it among the most aerodynamic in its class. Airflow management over the exterior, below the under floor and through the air passages was extensively examined. A unique gull-wing-shaped roof-panel design reduces mass and overall vehicle height, thus reducing drag and improving fuel efficiency. The front spoiler, rear spoiler, rear under spoiler, and diffuser fins all reduce turbulence. Smooth A-pillar shape and the optimized angle and curvature of the bumper side panels also reduce wake turbulence, as does the increased taper of the fender side panels. The under-floor covers have been optimally positioned for reduced drag, while airflow restriction in the engine compartment has been lowered by optimizing the air-duct profiles around the radiator.