Car Ferry for Sicily back to Mainland Italy

Hi- We're flying to Sicily in December, renting a car at the Palermo airport, and plan to take it eventually to Sorrento. We intend to take the car over to the mainland on a ferry on Saturday, 29 Dec 2012 to visit Calabria. Does anyone have specific information about ferries that take autos from the vicinity of Messina to either Via San Giovanni or Reggio di Calabria on weekends in December? Thanks so much -- online searches so far have been frustrating.