[3] Built on the Toyota New MC platform,[4] it is classified as a compact under Japanese regulations concerning vehicle exterior dimensions and engine displacement.

Unveiled at the North American International Auto Show in January 2009, the HS 250h went on sale in July 2009 in Japan, followed by the United States in August 2009 as a 2010 model.

The HS 250h represented the first dedicated hybrid vehicle in the Lexus lineup, as well as the first offered with an inline-four gasoline engine.

[10] Lexus displayed the HS 250h for the first time at the North American International Auto Show in 2009, with plans to launch the vehicle in major world markets including the U.S. and Japan.

According to division officials, the HS was produced in response to consumer interest in dedicated hybrid models, with many stating that they would purchase such a vehicle if a luxury make offered one.

In July 2009, the HS 250h made its sales launch in Japan, with 1,500 pre-orders logged at its introduction.

[14] The Toyota Sai, a sister model sharing the same platform and hybrid drivetrain, was launched in Japan in October 2009.

[15] However, HS 250h was not slated for the European market, where the similarly sized IS 220d and Toyota Avensis were sold.

[20] The HS 250h engine runs on the Atkinson cycle, and the powertrain uses a continuously variable transmission.

[18] A 41-kilogram (90 lb) nickel metal hydride battery situated between the trunk and rear seats serves to power the electric motor.

The LKA system, operating in conjunction with the radar adaptive cruise control, helps keep the vehicle in its lane.

[22][23] Because of the higher than expected demand in Japan, Lexus lowered its allocation and sales plans for the United States in October 2009.