Probably the show with Jack Palance(was in motion picture Shane in the early 50s and City Slickers in modern times). He drove many different old cars from his collection in the show. Check in IMDB.com under his name for movie/TV listings.
OK, it was probably William Conrad in the show Cannon. He was the original Matt Dillon on radio in Gunsmoke. Couldn't make the transition to TV because he was round and short so a young James Arness got the part.