I made the mistake of renting a GPS when I traveled to France while filming a documentary.
You'll never need a GPS again if you know how to download Google Maps Offline!
SOME HELPFUL TIPS
I've run into the issue where I didn't download the proper section. It will tell you that it's unable to direct you to your final destination. Give yourself some extra wiggle room on the map to avoid this by zooming out before saving.
Prep the night before and save yourself the stress in the morning. JFK airport does not have free wifi so if you're flying to Europe out of JFK I would advise you download your map to your first Airbnb or Hotel before you fly out.