When I think of cars from the 1950's, one car stands out above all others, the 1957 Chevrolet Bel Air. This is not to say there aren't other great cars from that era--Cadillacs, Ford Thunderbirds, Oldsmobile Rockets, Buick Specials, Hemi Powered Mopars, just to name a few. There are also brands which were in their decline or died out in the time period like Hudsons, Packards, and Studebakers. And the 1955-56 Chevys are great as well.
But to my eye, the '57 Chevy is THE car of that era. The twin headlights and front bumper with its mass of chrome. Rounded fenders and a shoulder line that flows towards the back, with a kink just as the tail fins start. The fins themselves are tastefully restrained--they don't jut up or out and are not laden with chrome like some of the Chryslers or Cadillacs of that era. The whole car is nicely proportioned and looks right, especially in two tone paint.