June 2000. The serial number part of my VIN is in the 4000s. Do I win? Trivia: Gen1s came from Toyota's Motomachi plant, in Toyota city, Aichi prefecture. TOYOTA MOTOR CORPORATION GLOBAL WEBSITE | 75 Years of TOYOTA | General Status of Plants in Japan | Motomachi Plant says "2000, May: Prius production commenced; Prius production transferred from Takaoka Plant". It also says "2003, May: Prius production ended (cumulative production: 33,411 vehicles) and transferred to Tsutsumi Plant". For some reason, possibly from an early TSB, I have a figure of about 80,000 Gen1s stuck in my head. I don't know why that doesn't match Toyota's figure of 33,411 vehicles. The Wikipedia article is also all over the place on manufacturing figures.