Considering that a pretty large kudu cow managed to traverse the entire vehicle front to back doing incredible damage I think it's safe to assume the driver was not doing anything reasonable in terms of speed. You just have to look at souther Africa's record for speed-related road deaths to figure that one out.
But who knows - that may have been the Usain Bolt of the kudu world ...
Doubt it though. Happy to be proven wrong but I'm going with prior experience on this. I have lived in southern Africa for something in excess of 45 years, so have some experience to draw on.
And no, before you suggest it, I am not basing this in any way, shape or form on the colour of the driver!