I have just returned from a week in Sicily where a car is essential should you want to explore this wonderful island properly. Driving however is extremely nerve wracking and very, very, frustration.
Pack extra BetaBlockers if you drive in Sicily! I have driven in all parts of Italy but nothing prepares you for the crazy "death wish" drivers of this island. On nearly every journey we encountered these kamakazes who think nothing of overtaking on blind corners and consider the depth of a cigarette paper as the correct distance to place their front bumber against your rear one, regardless of speed!
If that isn't enough to cope with, you must also be aware that signpostng is truly terrible. Usually there will be good signage on the motorways but once you come off do not rely on any of the signs (if there are any) Many point in completely the wrong direction or will take you on a 100km detour. Buy a map and trust only your own instincts as to when to make critical turns. This is particularly true when driving through towns en route Roundabouts are a particular nightmare because suddenly you will have the choice of 3 exits with not a single sign on any of them, so keeping to the right road becomes a lottery.
Good luck and don't even think of not taking out full and comprehensive insurance for your car and your life!