OK, perhaps I’m still a city planning nerd, but this graphic below on city density and gasoline use per person is totally awesome. Basic point is a simple one: people living in denser cities drive less. However, it also pulls out another interesting point: density aside, some countries (and continents) seem to promote automobile use (and/or inefficient automobiles use) more than others. Australian cities with similar densities as U.S. cities don’t burn as much gas. European cities are mostly dense, but even when they compare in density with cities on other continents, they rock the show on gasoline use (meaning: they use very little).
Of course, this isn’t a comprehensive look at the matter, but I think it’s a pretty good representation of some important points, so here it is: