If you have a smartphone with you, you could simply use that for navigation and forget about the car system until you get back. Google Maps is free and works well, you can download offline maps to use it without a data connection if you want. Used that for a months touring of New Zealand without any problems, even in areas with non-existent cell coverage. Other free satnav apps are available, also with offline maps. You might need to invest in a cheap mount to hold the phone in a suitable place.