if you rent a car in France, do not assume that you are allowed to take it into Italy. Apparently Italy is notorious for car theft, break ins, and vandalism in addition to accidents. It might depend on the agency and vehicle class, but on Hertz rentals, they have put in my contact that the car will stay in France. It is easy to get permission for some countries such as Belgium at no charge, but this must be in the contract or you risk, for example, having no insurance cover at all. They tend to say absolutely no for Italy, even at a surcharge IME, for a single over 25 driver with an automatic that gets an upgrade.

I would advise you not to rent a car, especially if you have never driven much in Europe. Some hotels can arrange car service for a wine tasting day.