Do you have a round in the chamber and where in the car is the Shield? Glove box, center console, lock box, under the seat, holster like carrier?
I carry with a round in the chamber in a holster because having to chamber the round takes time, requires two hands and is another way for something to go wrong.
But if you will have time to retrieve the gun from under the seat or a glove box if you need it you will probably have time to rack the slide and chamber a round too. If you are worried about kids or grandkids finding the gun most of them will lack the strength to rack the slide, its more of a deterrent than a safety. And you would not have to go through the process of buying a new gun in what sounds like a restrictive state.