My memory of why former New England mob boss Francis Salemme – had received the nickname “Cadillac Frank” was because at one time, he worked on Cadillac cars at a garage in Boston. Francis P. Salemme [Salemmi], also known as "Cadillac Frank" and "Julian Daniel Selig" (born August 18, 1933), is a Boston, Massachusetts mobster who became a hitman and eventually the boss of the Patriarca crime family of New England before turning government witness. Wikipedia