You'll want to pay attention to the fuel policy - see my comments in this thread: http://www.flyertalk.com/forum/spain...ar-rental.html

Also note that queues for Goldcar in PMI can be horrific. If going with them at peak times, I'd recommend paying for queue-jump. Some of the other cheapo operators can have very long queues too.

Actual driving in Mallorca is fine, as long as you're not expecting American roads. If you're staying at a villa, it may be down a very narrow track - always take care.