I love driving, we did 3,000 miles on our two week trip, but... that's a lot of driving!
I do to, so the idea of driving a 4-6,000 mile loop is no big deal. However, for people from the UK, the thought of driving those miles may be a little intimidating. :>)
On the positive side, in the area that he is considering seeing, the "attractions" are spaced such that a lot of miles can be driven late morning>early afternoon and/or at night and save the good light for photography.