Book a ferry ride from Split to Ancona not sure about make and model of vehicle

I am looking to book a ferry ride from Split to Ancona for 4 on September 5th this year but as of now I don't know what make and model of vehicle we will be traveling in as I haven't figured out a rental vehicle yet. Is there a way of booking the ferry now and updating my vehicle information closer to the date?

Yes it is possible – select vehicle type as ‘other’, enter the dimensions you expect the vehicle to be and then enter vehicle registration as ‘unknown’.