DETROIT – Toyota Motor Corp.’s Lexus brand debuts the all-new HS 250h today at the North American International Auto Show here.

The ’10 HS 250h, going on sale in the U.S. in late summer, is the luxury brand’s first dedicated hybrid-electric vehicle and also the first in its lineup to be powered by a 4-cyl. engine.

A top Lexus official last month told Ward’s that despite a drop in fuel prices from last summer, he believes the HS 250h will be a success, based on the fact many Prius buyers have 6-figure incomes and some already have a luxury car in their garage.

“We have Toyota dealers who tell us they can only sell (Priuses) that are fully loaded,” Mark Templin, group vice president and general manager tells Ward’s.

“People don’t want base models. That tells me those customers want more. They’re probably good candidates for Lexus hybrid cars.”

The HS 250h has a 2.4L 4-cyl. Atkinson-cycle engine that together with an electric motor generates a total 187 hp, Lexus says.

While not divulging fuel-economy estimates, Lexus expects the car to achieve 30% better results than the brand’s most fuel-efficient model, the upcoming ’10 RX 450h front-wheel-drive cross/utility vehicle with an estimated combined fuel economy of 28 mpg (8.4 L/100 km).

As with the new RX 450h, the HS has a variety of fuel-sipping technologies, including the same exhaust-heat recovery system, cutting the time needed for the engine to warm up and also stopping it earlier and more often.

Also present is a cabin-cooling windshield with infrared-ray reduction properties, lessening the need for air conditioning. Power-saving light-emitting diode headlamps also contribute to fuel savings and cut emissions, Lexus says, adding the HS 250h has been certified as a Super-Low Emissions Vehicle.

Reducing turbulence that contributes to drag was a key focus of the HS 250h’s development. Front and rear spoilers, a rear under spoiler and diffuser fins help the car achieve a low drag coefficient of 0.27. Lexus says the Cd rating is among the lowest in the HS’ class.

Additionally, a “gull-wing-shaped roof-panel design reduces mass and overall vehicle height, thus reducing drag and improving fuel efficiency,” Lexus says.

Noise, vibration and harshness have been minimized with the use of dynamic dampers placed at each engine-mount point and thicker suspension mounting points. Additionally, power-window speed controllers, borrowed from the Lexus LS flagship sedan, close windows more slowly and softly than typical speed controllers.

The HS 250h is sized between the Lexus IS and ES midsize sedans. It is longer than the IS at 184.8 ins. (469 cm) and taller than the ES and IS at 59.3 ins. (151 cm).

No word on what architecture will support the HS, although Templin told Ward’s in December the car’s platform is shared with “probably 12 cars across the world.”

Some parts of the HS interior are made of what Toyota calls “Ecological Plastic,” including the cowl-side trim, door scuff plate, tool-box area, floor finish plate, seat cushions and a package tray located behind the rear seats.

Lexus claims the bioplastics’ use in luggage-trim upholstery is an industry first.

“Ecological Plastic emits less carbon dioxide during a product’s lifecycle than plastic made solely from petroleum,” Lexus says. “Over the estimated lifecycle of the vehicle, the HS 250h will have approximately 20% fewer CO2 emissions as a result of utilizing the Ecological Plastic trim pieces.”

Some 30% of the HS interior and luggage area is covered with the bioplastic, Lexus says.

Like the new RX, the HS gets a Remote Touch controller, similar to a computer mouse, mounted on the center stack and allowing the driver to control the navigation system’s functions.

The HS also features the same casual-speech voice-recognition software as the RX, which is part of the new Lexus Enform telematics system that is slowly being rolled out for the entire Lexus lineup.

The HS navigation system is a hard-disk-drive type, with a screen that retracts and is positioned “well back and up front in the dash, (improving) visibility and reducing driver-eye movement,” Lexus says.

Other interior technology features include Bluetooth, satellite radio and USB iPod connectivity.

The multi-information display, part of the hybrid system indicator gauge, can be accessed via steering-wheel-mounted controls, Lexus says.

Standard safety features of the HS 250h include 10 airbags; active front headrests; and electronic stability control, with an optional pre-collision system.

Also optional is a wide-view front monitor that uses a front-mounted camera to show hard-to-see areas, and a lane-keeping assist system, which adds smooth torque from the electric-power-steering motor to keep the vehicle centered in the lane.

The EPS motor is brushless and mounted on the steering column, improving the rack-and-pinion system’s feel, lessening harsh feedback and improving emissions, because it doesn’t drain engine power to the extent of conventional hydraulic steering.