Hi,
I just want to share some information from my recent experience driving from Windhoek to Walvis Bay and back.
I wanted to do a more scenic route than the regular tarmac road and had read about people recommending to drive the more scenic road named C28.
I want to advise that the C28 is no walk in the park and unless you are an experienced driver in a solid 4x4 vehicle you should probably consider to avoid this road! I was surprised as to how rough this road was to drive and I found little time to enjoy the scenery as it was such a challenge. Please understand that this road is rough gravel from Windhoek almost the whole way to Walvis and there is not a single petrol station between the two cities. It took me 4 1/2hrs without stopping and there is a lot of steep hills. I only met 4 cars in 4hrs so you are pretty much alone (at least for a while) should something go wrong. I would not recommend this for motorcyclist either, unless you are looking for a very big challenge.
On the way back I took the C26 and I enjoyed this a lot more. Don't get me wrong, this is not a walk in the park either as the roads are gravel and there is still not many cars or any petrol stations, but the roads are better and there is not as many hills to embark. I also found the scenery much more spectacular than the C28 and I really felt the African experience that I remember from Tanzania. I would recommend a big 4x4 (I drove a Nissan Pick Up) but you might be able to do the C26 it with a smaller SUV, although I would not recommend it. I would also say this is a good and challenging road for motorcyclist's and it took about the same time to drive, around 4 1/2 hrs.
Note: I rented my car from Dollar/Thrifty and was not too happy about the long time it took to get the car ready (45mins). Upon return you can't fill up the car at the airport so I refilled full tank before leaving Windhoek (about a 35min drive?) and still it seems they have slammed me with a ridiculous charge of 1200 N$ to refill the car!!! A full tank cost about 700N$! I'm investigating this further but they have not replied to my emails yet so take this into consideration when renting a car from Windhoek Airport.