Just a layman's question - Isn't it possible to just disable this Navigation system with a password before leaving your car in a parking lot?
That would create all the trouble for the thief to force him to use other methods of stealing your car and reaching your house.
Good suggestions, although as was pointed out, if a car thief wants to know where you live, all he has to do is look at the registration -- and then the navigation app on his smartphone can give him turn by turn directions to your house. No in-vehicle nav system required.
In some parts of the country, if you don't quickly discover that your car has been stolen, about the only think LoJack or OnStar can tell you is where in Mexico your car is located.
First, don't store your garage remote in your car.
You could manufacture a GPS that would allow the owner to set passwords on certain destinations or areas. For example, you might require a password for any destination in your home city or county. Obviously, thieves could still drive to your home using a paper map.
You could design a GPS integrated with the ignition that would not allow the vehicle to be driven in your home city without correct password entry. If it's a built-in GPS, you could have this capability even if the thief isn't using it for navigation. A thief could still take your registration and steal another car to get to your house but at that point he or she is likely to consider your house too much hassle and go looking for easier pastures to rob.
I recently rented a car, with a stand-alone GPS from Garmin. To activate the GPS the first time, you had to enter a 6-digit PIN that was on the rental agreeent, and do it within 24 hours of getting the car. (If you didn't do it within the 24 hour period, you were locked out and had to call to get a new PIN, as I found out the hard way.) The rental company is concerned about their GPS unit being stolen, in this situation.