Moyogalpa is the place to go to rent cars and motorbikes, although a couple of places in Playa Santo Domingo rent motorbikes. Car rentals run as much as US$90 per day (check at Hotel Ometepetl). Motorcycles cost US$25 per day (US$5 per hour), and bikes will run around US$5 per day.
If you have your own car, consider leaving it in the parking lot by the San Jorge ferry terminal, particularly in the wet season if you don’t have a 4WD. Ferries can transport your car; make reservations well in advance.
Taking a car to Ometepe involves a bit of forward planning, some runaround and cash. Since rental cars on the island can cost upward of US$90 per day (when available) and public transport is patchy at best, it may just be worth the hassle. Four-wheel drives are best for the spiky volcanic roads.
To do it, get here for the first ferry from San Jorge to Moyagalpa by 7am. Ferries leave about every hour. You should be able to make it by noon with a little luck. There are a handful of ferry companies at the Moyagalpa terminal, but the central Empresa Milton Garcia is best to help you buy your tickets and arrange passage. With the port tax, mysterious 'car tax' and ferry transit fee, you'll pay about US$20 each way. Passengers buy separate tickets.While the companies say you can arrive that day and get on a ferry with a car, you're better off calling ahead.