On the B4 from Keetmanshoop to Luderitz. The drive is well over 300 miles between the two, but fortunately a good portion of it is actually paved, which is somewhat rare in Namibia.
Something I get asked a lot is, isn't it boring to travel independently? Over the course of two weeks, I covered over 2,600 miles, most of which was on unpaved roads traveling under 50mph (if not much slower), on my road trip. There were many days where I was spending 4-5 hours if not 8hrs or so driving.
It's not the same as driving in the US as traffic doesn't exist. You can drive 10-20 miles easily without seeing another vehicle, and when you do see one, it's going in the opposite direction as you are. I found it largely a bit relaxing to just drive and drive, enjoying the beautiful scenery, listening to music, and pulling over whenever I felt like it to take some photos.
B4 Highway from Keetmanshoop to Luderitz, in southern Namibia.