i can confirm as greaseman85 says that the gps sd card is registered to ur vehicles unique vin and cannot be transfered or altered in anyway. you would have to purchase another sd card through the dealership or from the gps website (im drawing a blank on the provider name there) and download it to ur own sd card.
Well, the SD card really helps to make updates easier and faster, but of course the car companies still want to make maximum money. Up until a couple years ago car navigation wasn't even on an SD card, it was just installed in a built-in non-removable storage unit. Updating it either required going to the dealer or buying a USB drive with the updated maps from the map maker.
At any rate, I mostly use Google Maps. It is far superior to any car navigation or portable navigation units. And it is free and you get much more frequent updates. I think Android Auto will put many of these map makers out of business in a few years.