Arragonis- we're a lot more decentralized than Europe, and decentralizing things makes for lots of inefficiency. You've got more rail over there, sure, but
Wikipedia says that Western Europe has 165,331 km of rail (I just zipped down the list and I know I missed Portugal with its 2,842km) while we "only" have 226,427 km. Out here, you've got to have your own infrastructure, and some way to "haul stuff" is a big part of that.
Hatchbacks and wagons are really effective at that, but mpg requirements actually killed them here because the requirements weren't paired with meaningful gas taxes- people got the same utility (and more manliness) by buying an SUV that didn't have to meet the same requirements as cars. Since gas was so cheap for so long, there was no real incentive for people to buy cars instead of trucks. Add a little shortsightedness about real costs and a lot of marketing, and you wind up with a country full of chromed out quad cabs with V-8s.