I want to drive from Montepulciano to Rome on a Sunday in early June. I need to arrive by 10:00 am and want to know if traffic is minimal on Sunday. I would leave that evening around 8:00pm. Could take train possibly if better. There will be 4 to 6 of us.
Frank, you did not tell us where in Rome you will be going. On one of our trips we picked up our rental on a Sunday morn at the huge auto rental lot under the Spanish Steps/ Bourgesee Gallery. It was quick and easy. ( A GPS really helps) If you want to avoid driving in Rome, drop your car off in Orvieto, and train to Rome. A great option.
I would take Rick's advice and park the car in Orvietto and take the train in to Rome. The train station at Orvietto has a huge parking lot that is secure and free.