It would take you about 88 and a half hours, or about 3 and a half days.
UPDATE
Realistically, given multiple border crossings and other bureaucracy, it will be more like several weeks. The hard part is Sudan and Southern Sudan. Egypt has good to medium roads. Southern Sudan does not.
You have to travel on a ferry along the Nile for a while as well, as there are no roads parallel to the Nile, which is very slow.
Once through Sudan and Southern Sudan, you can drive through Kenya, Tanzania, Malawi, Zambia, Botswana or Zimbabwe and then South Africa through to Cape Town. The main roads are mostly tarred from Kenya onwards though not necessarily in good condition.
In South Africa much of the drive is double lane highways in good condition.
If you like beaches come through Kenya, Tanzania, Mozambique, South Africa along the east coast. Its very pretty, but slower and you need a good 4x4 vehicle. Toyota is best as spares are available anywhere.
The drive is approximately 4 hours long.
1 1/2 hours
4 and a half hours to 5
8 and a half hours in the car
1,459 km16 hours 46 mins
The approximate travel/road distance can be around 404.47 km to 439.64 km. However, how long this takes depends. The Distance between Cape Town (Western Cape) and Oudtshoorn (Western Cape) is : 351.71 kilometers (km).
The distance is 670 kms, the time factor is your decision
The flight from Cape Town to Johannesburg takes 2 hours.
There is a VANS shop in long street, Cape Town.
The flight time from Beijing to Cape Town Is : 16 hours , 5 minutes
if you go over the N7 en B1 around the 19hours that's 1.478 km
too long...