We clocked up well over 3000 miles.  Comfortable coach, though, and good roads mostly.
Take lots of music to capture the mood at each stage of the journey.  I feel that we missed a lot along the way and I really want to do this tour again.  But I can't recommend this trip enough.  A real adventure. Choose a good guide book.  Be relaxed about fellow travellers - it's an epic journey.  Have a great time!