Question Can You Take Rental Cars on Ferries in Greece?

I'm planning a trip to Greece and want to explore places like Monemvasia and Kythira. I'll need to take a ferry to Kythira and am considering renting a car in Athens to use throughout my trip. Does anyone know if it's possible to take rental cars on ferries in Greece without any issues? I'm trying to figure out if it's practical to rent a car in Athens and use it across different islands or if I should look into other transportation options. Any advice or experiences with this would be really helpful!