I'm looking to get to Ilha Grande from the GIG airport. I see there are some transfer services, but they're not particularly cheap and the shared ones can make you wait at the airport for pick-up. On the other hand, I see that car rentals are cheap: like US$25/day all in for a small automatic. Is there anything difficult about renting a car at GIG and driving oneself to the Ilha Grande ferry dock? From what I can tell, there seem to be secure parking lots at the docks.