renting a car in Santorini is definitely a good option as the island is relatively “big” and it will give you a lot of freedom. Parking is obviously limited. Last summer, it was not a problem at all to park. I was there again last June and it was not crowded yet. This summer is certainly busier so more difficulties can be expected. You should first check if there are cars available and at which rate. Because as you know, there is a shortage of rental cars worldwide and prices have gone up crazy.