although permission to begin full production of passenger cars in japan was not granted until 1949, limited numbers of cars were permitted to be built from 1947, and the toyota sa was one such car. design work started at the end of 1945 when the ghq let it be known that authorised commercial production of vehicles for the general public would be commencing soon. this model was introduced in january 1947, with a prototype (which had been under development for more than a year) being completed at that time.