Toyota's new Sai hybrid, introduced at the 2009 Tokyo auto show , is a rare example of a piece of Japanese technology appearing first in the U.S. before migrating to the homeland. What's more, it was initially introduced as a luxurious Lexus and then demoted to Toyota status.

The Sai employs Toyota's by-now familiar gasoline-electric hybrid technology, and is built on the bones of the Lexus HS250h . In this application, as in the HS250h, the front-drive system employs a 2.4-liter Atkinson-cycle four-cylinder gasoline engine (147 hp, 138 lb-ft of torque) and a robust electric motor rated for 141 hp and 199 lb-ft; the system's maximum combined output is 187 hp. Toyota projects combined city/highway fuel economy at about 47 mpg in Japanese testing, while the HS250h gets a 35/34 mpg city/highway rating from the good ol' EPA.

Like other Toyota hybrids, the Sai can operate as a pure electric. It offers three driving modes, one (standard) providing a conventional mixture of gasoline and electric power; a second (Eco-Drive) that reduces interior electrical power draw (e.g., low-energy air conditioning); and a third (EV) that operates the car on electricity alone. The HS250h is capable of two to three miles of EV range--if the driver is light enough on the accelerator--so we expect the Sai to be similarly capable.

As it does wearing Lexus badges, the slick body shell has a coefficient of drag of just 0.27. Toyota positions the Sai as a luxury hybrid in Japan, with a comprehensive array of standard features, including a nav system, plus a long list of passive safety equipment.

Sales of the Japan-only Sai begin in December. Given the existence of the Prius and Lexus HS250h, the Sai isn't likely to find its way to U.S. Toyota showrooms.