The way I see it is that he has convincingly portrayed staged photographs of real show cars. In other words it looks like somebody took some nice cars and cleaned them up really nice to be photographed.

Weathering definitely is a great way to add to the realism though. Adam Savage (mythbusters guy) has some great videos on Tested of using various weathering techniques to make props look incredibly convincing: http://www.tested.com/art/makers/453823-one-day-builds-adam-...