I have formerly included GPS with auto rental in Europe, but if you drop auto in different location than where you rented it you'll be hit with at least an extro 50 Euros drop fee, in addition to upgrade costs for the auto. Also, some locations in Italy (my experience in Florence) will not permit return of GPS unit to a separate location. And, they remind you that if you lose the unit you'll incur at approximately $300 fine!
I took the time to download "Western Europe" navigation map on my portable "Tom Tom" Model 340-SXL unit, which cost approximately $60 and took some five hours to download, but it saved me $100. Now, I, and my other family members, can use this on other trips throughout Europe. If you consider same, suggest you back up your GPS on computer before downloading new maps, as most units do not have sufficient memory (storage) for additional maps that might have come with the unit.