My guess would be that most of the people who carry a concealed handgun for their personal defense have never practiced their pistol presentation from behind the wheel of their car. Yet, when you think about the amount of time that we spend in our cars, it makes sense that we might have to deal with a criminal attack while sitting behind the steering wheel.
Humor me, unload your firearm, check (twice) to be sure the chamber is empty and go out right now and try it. I can wait. But, please don't cheat. Wear your defensive handgun in the usual position, wear your covering garment, and don't forget to buckle up.
It wasn't easy, was it? Your steering wheel gets in the way, your seat belt interferes and, if you are carrying on your strong side hip as most do, you are sitting back against your gun and don't have enough room to move forward to access it. It's pretty easy to get tangled up in all that stuff.
Some might solve this issue by off-body carry when in the car. Some have a gun in the console. Others have it in a container on the passenger seat. But do you really want passengers, especially children, to have such easy access to your defensive handgun? And where will that handgun go if someone rams your car with theirs?
For most folks, a cross-draw carry, while driving, will work pretty well. For others, myself included, a good shoulder holster will work better. The idea is to be able to make a pistol presentation without even having to remove the seat belt. And, since body sizes and shapes differ so much, you just have to experiment until you find what will work for you. Your goal in this experimenting should be to accomplish a 1-second draw while still buckled in and behind the steering wheel.
Think about speed, because the crooks aren't going to give you much time to respond. And think about security, because you don't want the gun to go flying if you're in an accident, and you don't want it to be easily available to unauthorized persons. After you have done some experimenting (always making sure to be safe with an unloaded, double-checked firearm), while actually in your car, get back to me, because I'd like to know how you resolved the problems.
