You can also rent a personal wifi hot spot. I did that in Japan and it was great.
This.
My old Nuvi has been our navigation system for the last several years now. Came pre-loaded with Europe and North America.
Be a little careful with France as some older car GPS which highlight speed cameras are illegal. (rather, highlighting the often fixed cameras is illegal). Newer ones turn this off or show ‘danger zones’ as a way to be legal. Best to google search your model and compatibility with France. (I think just France… maybe some other European countries are also similarly strict).
Google maps has launched offline navigation for Android. You have to mark the area in advance, but you can do this on WiFi at a coffee shop if you need to.
The only gotcha is that phones have very weak GPS without access to cellular networks, so you’ll get much better results if you use a low-data plan to get a lock and then turn off cellular data.
Last fall we picked our car up from Eurocar with GPS option. The supplied GPS was terrible.
Few years ago my other half had a car with a TomTom GPS that worked very well driving in Paris and nearby.
I am in Europe several times a year and just use my iPhone with a GPS app called CoPilot, which works great. I download the maps I need here, then navigate over GPS (not cellular data) over there, so no concerns about data charges. I think all-in I’ve paid something like $40 for the app and maps of most of Europe’s wine producing countries.
While I use and am happy with CoPilot, a quick search turns up a couple of other similar apps listed in a recent WIRED article here – http://www.wired.com/2015/04/offline-gps-apps/