I wonder if there are any other countries in the world where the best-selling automobile is something completely impractical? Or are Americans unique in that regard?

Serious question. I can't think of any, but I'm also not familiar with car markets the world over. In Japan, for example, the best-selling car is the Honda N-BOX [1], which is an incredibly practical car.

[1] https://car.watch.impress.co.jp/docs/news/2076520.html