The Fiat 509 was a series of cars built by Fiat and first introduced in 1924. Powered by a 1.0L inline four engine, the 509 saw a few main variants including the 509A, 509S, and 509SM. The 509A was an upgraded base model, where the S and SM were sports variants. Built in open or closed top body styles, the 509 was in production until 1929.