We have sailed out of Miami on cruises a number of times. Each time we have rented cars from Alamo. They provide a free shuttle service from the airport to the port. We normally drive down from Orlando, drop the car off at the airport and catch the free shuttle to the ship. The shuttle will drop you off right on the pier by the ship. On return the shuttle will pick you up at the pier and take you back to the rental desks by the airport to pick up your car for the return journey to Orlando.

Our last couple of cruises were from Ft Lauderdale so we haven't used Miami since the new car rental centre opened at Miami airport where all the car rental desks are centred in one location. However, they have recently built a car rental centre at Ft Lauderdale and the same system was in place there so don't think anything will have changed. I know there are other regular cruisers on the forum who may be able to confirm this.

Enjoy your cruise. Your sure to have a fantastic time!