In the Nanocar race competition the molecules are raced on a gold surface. Is there a specific property of gold that it forms a good "racetrack"? On what criteria does it compare with other metal surfaces?
While I can't find specific justification for the surface, the first competition involved both gold and silver "racetracks."
The competition involves propulsion and imaging using STM so the substrate must be conductive. Gold (and silver to a lesser degree) is particularly useful, since it won't easily oxidize and is easy to purify.
I've seen several comments about having 'tracks' in the gold surface, which suggests a well-defined crystal face with reconstruction, e.g. Au(100):
(Image from Wikipedia)