There is a Car Ferry Discount Program for Mexican plated Vehicles called Plan Cozumel. You must also have a Mexican driver’s license to qualify. It is vehicle and owner specific, in other words, if you have multiple vehicles, you must get a discount card for each. While you need not be driving, you must be in the vehicle to receive the discount.
At the time that I obtained this information, there was a big demand for the discount, so they were only processing about 85 per day. The guard on duty handed out numbers starting at 7 in the morning. One number is only good for one vehicle; ask for more if you have multiple vehicles.I was told foreigners should present their car registration card (Mexican) their Driver’s license (Mexican) and their Immigration Credentials. The discount card is free of charge, but replacement cards for damaged or lost cards will be 100 pesos. They are located on Calle 6 North #14 between 10 and 15th Avenues. They are open Mondays, Wednesdays, and Fridays from nine a.m. to two p.m. The cost for an economy car not exceeding 5.5 metros will be $723.98 pesos. The discount will lower that rate to $380 pesos. This includes the driver; extra passengers will be $60 pesos each.