Should travellers rent a car in Greece?
A car is useful in Crete, the Peloponnese and larger islands, but it is not automatically useful everywhere. Rent it for beaches, villages and ruins that need reach; skip it where parking and ferries will do the annoying part for you.
Answer
Greece is not one car-rental answer. In Athens, a car is usually more burden than freedom. On small or highly connected islands, it may only create parking stress. In Crete, the Peloponnese and larger island bases, a car can change the trip completely, opening beaches, monasteries, villages and archaeological sites that public transport makes awkward. The decision should follow the route, not a general rule. Check current rental, licence and insurance requirements, then rent for the days where the car actually earns its keep.