You can make a cup of coffee at home and go for a walk around Civita with it while there's nobody there! Incredible experience! Cafes open in the morning for you to have a nice breakfast in the street.

We stayed close to the Re di Roma square. There's a good parking garage where you can park your car for a couple of days to walk around Rome on foot. It's much more convenient than driving. And you cannot drive in the historical centre.
But still, you always can take your car back and drive outside of the city if you want. We did it for some shopping in the malls close to the FCO airport when our legs were dying after about 30km of strolls in the city.