TORRANCE, Calif. --- Toyota Motor Corp. announced that the Toyota Prius, the world's first mass-produced gas-electric hybrid vehicle, has surpassed one-half million worldwide cumulative sales with 504,700 units sold as of the end of April. Toyota launched the Prius in late 1997 in Japan. Its popularity in Japan prompted the launch of Prius in the U.S. in July 2000. The first-generation U.S. Prius was a low-volume unit (12,000 produced annually) that gained an immediate following among environmentally conscious consumers. The second-generation U.S. model was launched in the fall of 2003 as a 2004 model year. The 2004 Prius came with larger dimensions, new styling, and featured Hybrid Synergy Drive technology. Heavy consumer demand for the Prius triggered multiple increases in production. By 2005 Toyota was producing over 100,000 units annually for the U.S. market. In 2005, calendar year sales of Prius in the U.S. reached more than 107,000 units sold, making Prius the third-best selling Toyota passenger car after the Camry and Corolla. From the summer of 2000 through May of 2006, 266,212 Prius cars have been sold in the U.S., making up more than half of all Prius cars sold worldwide. The successful launch of the Prius encouraged Toyota to expand its hybrid technology to existing models in the Toyota and Lexus lineups. Lexus will further expand its hybrid lineup in April 2007 with the launch of the LS 600h L luxury hybrid sedan.