Robert Slovick has owned the 1934 Ford coupe since 1997.
He had invested $75,000 to restore it and said it is now worth $250,000.
"There's a reward. Please, you've got to bring this car back," Slovick said. "It means so much. You have no idea what you've done."
Anyone with information is asked to call the Garden Grove Police Department at (714) 741-5704.