The car driven by Columbo is a 1959 Peugeot 403 convertible. Only 504 two door convertibles were made in 1959. The original was sold when NBC dropped the series, and a replacement had to be located when ABC resumed production.
Originally, Bing Crosby was offered the role of Columbo. However, citing the fact that he didn't want to commit to a series, he refused the role. He also said, jokingly, that doing the series would interfere with his golf game.
Although Frank Columbo is a Detective Lieutenant in the L.A.P.D. he is rarely seen reporting to a superior or even interacting in any significant way with other police officers during an investigation. In most episodes he operates virtually as a private detective even to the extent of driving his unmodified personal vehicle while on duty.