For instance, many countries have restrictions on noise and Japan has taxes based on the dimensions of the car body. IIRC Europe has 95 RON fuel as the legal minimum rating. I guess this might be considered too confusing having to juggle all the regulations if you are marketing to a broad international audience, but it seems like it would make for an interesting and realistic challenge.
(I feel dumb posting these as separate threads as I come up with them, is there some thread I am meant to be posting to instead?)