Honestly, yourfirst priority should be getting out of your seat belt. If your firing from your car its likely that you are going to be either egressing or at least moving in your car more than your seatbelt will allow for. It may just be my personal opinion but I really think getting out of the seatbelt is the priority. That also makes of much easier to get to your gun no matter how you carry.lt gives you the freedom to move and not get your gun caught up in the seat belt.
We shot out of vehicles while at partner tactics at TDI. Yes, it was loud, but not much louder than shooting in a room. What was weirder was the brass getting everywhere and the feeling that you were going to blow a hole in your car. We practiced shooting our way out of the car and to cover while communicating with each other. lt's a lot of fun, actually.
when it comes to carry in the winter l leave my gun where it is and just open my coat for easier access. When I get the seatbelt out of the way the coat Is no longer an issue.