The future of Star Wars is coming into focus on this May the Fourth, with new film projects being announced during the annual celebration, but there’s a four-decade-old mystery tied to the franchise’s history that remains cloudy. In 1977, Toyota teamed up with 20th Century Fox for a promotional sweepstakes where the grand prize was a custom Star Wars Celica that featured imagery from the original film, including the movie poster painted on its hood and reproductions of film cells on the sides. Unfortunately, things didn’t go to plan. After the California shop that customized the car was mired in...