A 10-13h drive (with breaks) on a modern (say > 2009) car is surprisingly non-strenuous on US interstates. I've done it and it was not onerous. The driving experience in the U.S. is markedly different from other countries -- interstates are wide and relatively smooth-flowing outside major cities, and rest stops are plentiful.

To most Europeans a >10h drive sounds excessive, and that might be the case in certain parts of Europe, but the U.S. is (perhaps unfortunately, from an environmental perspective) built around the automobile, and the driving experience here is somehow different (i.e. easier).

I've driven in Germany and while I enjoyed spending hours cruising on the Autobahn (A-8), parts of the journey involved driving on tiny, narrow roads in small towns. Those segments were frustrating. I haven't yet tried it, but I don't think I'd be able to drive > 5 hours in Europe (but I could be wrong).