Last year I found hiring both easy and cheap. I had little desire to get involved with the implications of renting/driving/parking on our itinerary. TR in my signature block - F'hoek to CPT airport was ZAR900, or £50, in a shiny Merc LWB limo.

Depends on where you're staying in F'hoek and Simon's Town, of course. For us it was totally painless, especially as 2/3 locations had shuttle buses to local destinations.