Maps of South Africa including streets and roads in various towns, cities and regions across all provinces of the country are available to those looking for them online. Not everyone has a GPS car system and even those that do have them will at some point find themselves in a position to need a physically printed map either in an emergency situation or just as a back-up. They are reasonably cheap and worth folding up and keeping in the glove compartment or elsewhere in your vehicle for when you need it.
Not every one of the maps of South Africa are the same and it really depends on your needs as to which type you get. For example, if you need one for finding your way around streets in the city or a town then you may do well with a mapbook. If you are travelling across the country then you will need one which shows National roads and clearly indicates things like which are dirt roads and those that are tarred. Most of the good ones will indicate places of interest and some will even show the more popular guest houses and places to stay in and around SA.
Most of us have at some point in time got lost while driving and know how frustrating and difficult it can prove to be to find your way again. Also, with SA having a high crime rate it can be dangerous for tourists to get lost on route and end up in a not too friendly neighbourhood where opportunist criminals may be lurking. Even if you do have a good navigation system fitted to your vehicle have a look at and consider buying one of the various maps of South Africa available to you.