A car will allow some mobility - also try the ugly but delicious Salt & Pepper restaurant in Fira, and be sure to try some of the local specialties. Santorini is known for some of its produce - small eggplants and tomatoes with plenty of flavor due to the dry, sunny environment, so dishes like pseftokeftedes (tomato keftedes) and the fruits (like the local watermelon) are very good with lots of flavor. You will also see the grapevines growing like baskets, grapes growing "in the basket" to protect from winds and blowing sand - and it's well worth drinking some of the better Santorini wines.