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.
The very first episode, (aside from the two pilots) "Murder by the Book", was directed by Steven Spielberg and written by Steven Bochco. Spielberg was never again involved with the series, through Bochco wrote several other episodes.
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. The exception to this rule is provided in the "A Friend in Deed" episode that concludes season 3.