I just got home from a 12 hour, 747 mile drive to Virginia and back. Only stop I made was to drop something off, and a F.F.R. (food, fuel, & restroom break).
My back doesn't hurt, neither does my neck or posterior (usual for me after a long drive).
The West Virginia Turn Pike offered me some fun curves to deal with, and I saw my outside temp. gauge top out at 97 degrees. I saw 100 mph+ a couple of times too.
This car just keeps on amazing me. I felt like I could easily go a few more hours and still be comfortable.
Oh, I saw a yellow Ford GT in W. Virginia. But I never saw another XF the whole trip.