Driving in Tuscany

Buy a local SIM card from TIM or VODAFONE for €20 and you'll have all the data you need (2Gb).
100Mb aren't enough if you use it for GoogleMaps.
The best offline applications are from the well known GPS companies like TomTom and Garmin etc, but they aren't free, so in the end you would have to pay something. There are some free offline applications but I don't know how good they are for driving directions. I have used only GoogleMaps but always purchased a local SIM card. If you go that route, both TIM and Vodafone have a plan specifically for foreign tourists. They are called Welcome and Holiday respectively.

Last year we used a 5" Garmin and it was great. A couple of times there was some confusion with closed roads and then we supplemented with the iphone on a limited date plan. But the large screen of the Garmin was a solid benefit.

I drove in Tuscany by myself (68yrs old) in April for three weeks. I had a local Vodafone SIM card in my iPhone 6+ and a paper map of the area. Rarely had to use the GPS on my phone, a very easy area to drive, excellent signage everywhere, you'll find yourself driving very slowly to take in the beautiful views, and stopping often to take photos! I never did need the turn by turn directions feature. The only time I really needed the GPS was to find the Mate Winery south of Montalcino. They make wonderful Brunello wine!

I drove from Virginia Beach, VA to Cleveland, OH. Using Google Maps and turn-by-turn directions the entire 8 hour trip,. It used about 5 MB of data. 100 MB will give you a lot of GPS data time. Its not video.
GPS is not a data hog.

We are doing the same this fall. We reserved a mobile wifi device for about $10/day with unlimited data. Maps downloading with location can use up a lot of data. I've never used a mobile wifi in Italy, but have in other countries with great success. Perhaps someone else on this forum can give their 2cents on renting a mobile wifi in Italy. But ALWAYS bring a paper map.

You can also preload your destination before you leave on a trip in Google Maps, tap the 3 dots in the destination info and choose to save the map offline. You'll reposition and zoom the map to the coverage you need and hit save. Then if you are offline you can load the map from "Your Places" in Google maps. GPS should still track your location but the App will not give you turn by turn directions.

Each to his own, but I would suggest purchasing a dedicated GPS with European maps. They are relatively inexpensive and are, in my opinion, a great thing to drive. We have travelled three times in Europe and have found a GPS to be helpful. While signage may be good, in my opinion, having a gps is a great way allow you to explore back roads and get home safely. Enjoy you trip.

I agree the cost of a GPS on a car that is big enough for you to actually see is well worth the money! We did this several years ago and I would never go with just my IPhone. Just too small to see. Do you have a stand for it on your dash? You do not need to hold it in your hand and drive and even if your partner is telling you where to go, it is good to see it yourself on the map particularly in roundabouts where they tell you exactly which exit to take I know Google also tells you how to do this but I like seeing and hearing too! We will do 2 weeks in Tuscany in September coming in and out of FCO. We have a very good map which my DH will also be using as a back up. I've had too many bad turns, etc on GPS, so you MUST have a good map whether you do GPS or Google Maps. I am also a Verizon customer. I can assure you that 100mb goes very fast! Don't plan on using it for maps everyday!

We used an old iPhone 4s w a Vodafone SIM and used google maps and the native maps app on the iPhone and it went well.

Thanks everyone for all your responses. As we have two iphone 6's (present from son!), we will load one of them with the Verizon International calling (complicated to some degree because we are on a family plan and we are not the 'account manager') at 100mb, and for the second iphone we will purchase a sim in Italy with 2gb. Per Verizon, our iphone 6's are unlocked so there should be no problem putting in a different sim card in Italy(?). Again, thanks for your quick responses. I retired from hi-tech 22 years ago and find it more difficult each year to keep up - hence your comments were very useful and enlightening

Option 1: Rent a car with a GPS.
Option 2: Buy a GPS in the US with Europe Maps installed. Depending if you are going to use it again and again you can get one with lifetime maps for about $250 or with a one time install for $200 or less.

Remember: Smart phones are phones with maps, but a phone none-the-less. A GPS is a piece of electronic equipment designed from the group up to provide directions when traveling in a car. I bet you can see were I am going. Get a GPS. No data charges.