It's important to book a rental car in advance, because companies often have few vehicles available. If you expect to rent your car once you arrive in the city, you may not find any available. The earlier is the better! I always recommend using rentalcars.com to book a car online.

To rent a car in Italy, you must have a valid driver's license and your passport as proof of ID. You also usually need to have a credit card to pay for the rental deposit, though some companies will accept debit cards. You will also need a Collision Damage Waiver, which is a requirement in Italy.

Unless willing to book your days rigidly (in advance) and spend a lot of money on a driver or a lot of time waiting around for public transport, then you are going to need a car in Tuscany.