in the book that came with my gps it says to never leave it in the car unattended- i made a little quilted carrying pouch for ours- when we reach our destination i simply take it out of the car-
but all of your personal information is always in the car (or supposed to be) with your registration and proof of insurance- and any (suave) theif can easily get your address just from your license plate- public information-
anyone with a computer can quite easily find anything they want about anyone---with very little to go by.
it is best to (try) to take steps to protect yourself-
never leave anything in your vehicle anyone walking by can see and might want- always lock your doors-
it's sad that it's such a dangerous world- people who are desparate sometimes make really bad choices.