My guess is that it was illegal for them to go near Mars because there is no way to sterilize that roadster. We don't want Elon's microbes contaminating the pristine Mars environment I guess.
The final orbit goes out past Mars into the asteroid belt. It will loop back to Earth in a ~1.5 year orbit.
My earlier post on this very topic.
RE: How Will The SpaceX Roadster Degrade Over Time?