Hub to hub - does that mean you wake everyone at 3am to change trains? Nobody switches cars with humans in them.

> Nobody switches cars with humans in them.

What do you mean? Changing the train consist during the trip? That is exactly what they can do.

Hamburg/Amsterdam on one end, Innsbruck/Wien on the other. Those wagons get shuffled about like a deck of cards en route! So in Amsterdam there is one train with wagons marked Wien and wagons marked Innsbruck. You get in the right numbered wagon, and end up where you want. In the middle of the night, in the middle of nowhere (actually, probably München) they turn two trains into two different trains.

Most people never notice.