In reply to James Malloch:
No problems with Europcar recently, just make sure you buy insurance prior to renting, or else you'll end up paying their extortionate rates. Picking up and dropping off was straightforward, staff speak English, easy to find. They'll be my choice again when I head back there in the summer.
Driving in Sicily can be a bit mad, the secret is to be patient, relax, go with the flow and drive like a Sicilian