Went to Florida, picked up hire car at airport only to find no in-car sat nav so then had to hire one for far more than it would have cost to just buy one in Walmart
'Navfree is a free app for iPhone and Android. It turns a GPS smartphone into a data-free sat nav, with pre-loaded maps, route planning and voice prompts. It isn't a fully-fledged system like paid sat navs, of course, but it's handy for a one-off trip..store[s] all the map data on-board the phone itself, meaning you don’t need to use your Internet connection to navigate saving you money when you are traveling'
Hope useful - Thanks MSE