The islands road network has been sadly neglected for years now but despite this you can go anywhere with any ordinary small car, a 4x4 is not necessary, but it is a lot of fun.
No its serious 4x4 country side in fact big and heavy 4x4s will have a hard time negotiating the narrow roads and dirt trails, small jeeps or SUVs will do just fine.
The attraction of a 4x4 in Corfu is that extra sense of adventure to find some of those hard to find beaches or head off into the trails deep inside the olive forest knowing that the most dangerous things you might come across is a friendly local offering you coffee or olives.
But small jeeps can be uncomfortable to dive on the poorly paved roads for many days so most people prefer to rent a normal car and opt for a 1 or 2 day organised jeep safari. This is a lot more fun because you join a convoy of similarly minded people and enjoy not just the driving but also the parties that follow, not to mention a helping hand should you get stuck.
Another good reason to join a safari is the difficulty in finding a lot of the interesting trails, even with a GPS of lot of nice are simply not mapped, it takes local knowledge to save you from going round and round and yes I do speak from personal experience.
If you are tempted to take on these trails with a quad bike, which are very popular with the younger generations I would urge you to think twice. Quad bikes are notorious for inspiring confidence to the inexperienced rider but will tip over easier than a drunk Zorba dancer. They are far more dangerous than motorcycles and account for the greatest percentage of self inflicted road accidents in the world. You really do not want to come tumbling down the side of one of these mountains.