Motor Corp. will begin exporting about 20,000 of its Prius gasoline-electric hybrid sedans to the U.S. beginning in fall 2000. The Corolla-size car has been available in Japan since December 1997. There its price in yen is about equal to $15,500. So far it has sold about 7,700 units. The powertrain combines a 1.5L gasoline engine with an electric motor powered by a pack of nickel-metal hydride batteries.