Confirm everything below with your operator when you book. Vehicle rules are set by the maritime authority and applied by each company, and they have changed as electric cars have become common.
Book the vehicle space early, and separately
The single most useful line on this page. Car deck space sells out well before passenger space, and on the popular summer routes it goes months ahead.
If a Greek trip depends on having your own car on a particular sailing, that booking is the first thing to make, before the accommodation. What to book ahead covers the order in which Greek travel fills up, and vehicle space is at the top of it.
The vehicle has its own reservation attached to the passenger booking. Confirm they are on the same booking rather than assuming, because a passenger ticket does not carry a car.
Arrive earlier than a foot passenger
Vehicle check-in closes before passenger check-in, and the loading itself takes time. Operator guidance commonly puts vehicle arrival at around an hour before departure rather than the twenty minutes a foot passenger can get away with.
At Piraeus, add more, because the port is large and finding the right gate with a car in August is not quick.
Loading is efficient and tight. Crew direct you into spaces with very little margin, mirrors folded, and you will not be able to open a door once parked in some positions. Take out of the car everything you want during the crossing, because the vehicle decks are closed while under way.
Electric, hybrid and gas vehicles
This is the part that has changed and that most guides have not caught up with.
Greece has a regulation from the Ministry of Maritime Affairs covering the carriage of alternative-fuel vehicles, and it sets limits on the state a vehicle can board in.
Electric and plug-in hybrid vehicles are required to board with the high-voltage battery charged to no more than around 40 per cent, and this applies on domestic routes as well as the Italy crossings. Charging on board is not permitted.
LPG and CNG vehicles are required to have tanks no more than about half full.
Both are conditions of carriage rather than suggestions, and turning up outside them can mean being refused. Plan the charge or the tank level into the day before, which for an electric car means not arriving at the port with a full battery after a motorway run.
Confirm the current figures with your operator when you book. We have described the rule rather than reprinted a regulation we have not read at source, and the numbers are the part most likely to move.
The rental car problem
Do not assume you may take a hire car on a ferry. Many Greek rental agreements prohibit it outright, and others require written permission and additional cover.
This is a contractual matter rather than a maritime one, and breaching it typically voids the rental insurance entirely. Ask before you book the crossing, get the answer in writing, and read car hire excess and insurance in Greece for what that cover does and does not do.
The usual alternative is to hire separately on each island, which is often cheaper than it sounds once the ferry vehicle fare is counted.
Which trips it is worth it for
Worth it: Thassos, which is built around a ring road and where the crossing is short; the Ionian, where Lefkada is reached by bridge and Kefalonia is large; Crete and the long mainland-to-island runs where you would otherwise hire twice.
Not worth it: most Cycladic hopping. Vehicle fares on several legs add up quickly, the islands where you need a car are the ones where hiring locally is easy, and Skiathos, for instance, has a bus that covers the whole developed coast.
Which islands need a car works through it island by island.
Where this leaves you
Book the vehicle space first and separately, because it is what sells out. Arrive about an hour before departure rather than twenty minutes. If the car is electric, plug-in or gas, check the charge and tank limits with your operator and arrive within them. And if it is a hire car, get written permission before you book anything at all.
Quick answers
Do you need to book a car separately on a Greek ferry?
Yes. The vehicle has its own reservation alongside the passenger booking, and car deck space sells out well before passenger space, months ahead on the popular summer routes. Make it the first booking of the trip.
How early should you arrive with a car?
Around an hour before departure, rather than the twenty minutes a foot passenger can manage. Vehicle check-in closes earlier and loading takes time. At Piraeus, allow more, because the port is large and the gates are far apart.
Can you take an electric car on a Greek ferry?
Yes, subject to a charge limit. A regulation from the Ministry of Maritime Affairs requires electric and plug-in hybrid vehicles to board with the high-voltage battery at roughly 40 per cent or below, and charging on board is not permitted. Confirm the current figure with your operator.
Can you take a rental car on a Greek ferry?
Often not. Many Greek rental agreements prohibit it or require written permission and extra cover, and breaching that typically voids the insurance. Ask before booking the crossing, and consider hiring separately on each island instead.