Comment by _mitterpach

This might be completely wrong, since my understanding is based very much off of Truck Simulator games, but isn’t one of the reasons aerodynamics as well? The US is huge, and trips can take several days at high speeds, so aerodynamic improvements can save quite a bit of money, whereas EU is smaller, the trucks do not go at large speeds for as long and have to navigate tiny city streets, thus being more compact is an advantage there.