Per-capita number counts everyone, not just drivers, I imagine. More people drive in the US so it's natural per-capita travel will be more. The "wash" part makes no sense to me. Somebody shopping for a car when gas is 8 dollars will consider fuel economy more than when gas is 3 dollars regardless of per-capita travel distance. I am willing to bet that the vast majority of car shoppers cannot even estimate this distance for their country.