Judging by the images only, those are all the ones I called "European" trucks though, the American ones are much longer. Is that also regulated so European trucks aren't allowed in the US and American ones aren't allowed in Europe? Because here in Europe it's really uncommon to see the US ones, and I'm guessing it's the opposite in the US?

One of them must be better aerodynamically though, must'n it?

> despite air being the same everywhere.

The air may be the same everywhere, but roads and safety laws aren't.