In the episode "Life in the Past Lane" (#509), Nathan's retro-roadster looks like a standard 1957 2-door Ford Fairlane, until a later scene where he puts the top down. MTV's website identified the car as a 1957 Ford Skyliner. However, the rear roof pillar of Nathan's car is curved and not as thick as real Skyliners.

Nathan's Car:

http://www.imcdb.org/vehicle_48830-Ford-Fairlane-1957.html

1957 Fairlane Club Victoria:

http://1957ford.com/asp/gallery.aspx?catmstrid=1&catdetid=7

Real 1957 Ford Skyliners:

http://1957ford.com/asp/gallery.aspx?catmstrid=1&catdetid=1