I think you guys have me convinced. We will return the car in Naples before heading down to Sorrento and Positano. I guess if we change our minds we can always rent a car for one day in town to do some driving. Thank you so much to all for all your helpful hints and recommendations.

There is no place to rent a car in Positano. You would have to travel to Sorrento or Salerno to rent a car. But there really is no need with the ferries and taxis.