Without reading every post here so far, although I did read a few that contained a lot of good information, I will post my opinion based on training, experience and almost 40 yrs of working accidents.
1, Do not depend on being able to reach a gun in the glove box. If there is an immediate threat and you have time to get to the glove box, you also have time to drive away. LA has a Shoot the Carjacker Law but you have to be inside the car and the perp outside the car. Most perps will have you out of the car long before you can reach the glovebox.
2. Do not leave a gun in an unattended vehicle. A car is more likely to be stolen or pilfered when you are not in it than you are likely to be accosted while in the car. I have had two vehicles broken into in the last 15 yrs. The type person stealing your gun is not going to use it for the good of mankind. It will be used in other crimes or sold on the streets to those who will use it in crimes.
3. A gun in a car after an accident is expected in this area. Almost everyone has a gun in the car as they drive down the roads. After a disabling accident that sends the person to the hospital and the car to a salvage yard, the gun will usually disappear, seldom to be seen again. If the gun is strapped to a person, it goes where they go and the responding officer will secure the gun for the individual until they reclaim it.
4. If a person feels stongly enough about having a gun to carry one in their car, they should feel safer carrying it on their person. They will have more protection and will need less time to recover the weapon when or if needed.
5. Securing a weapon takes only seconds. I often pick mine up and carry it to the car as I leave the house. Then when I stop for breakfast, go into a store or such, I put it on my side in some form. If I have to go into a courthouse, I place it in a locked box that is inside a locked trunk that has an alarm system on the vehicle. As soon as I leave the courthouse, it goes back inside the vehicle with me. When I get home, it comes inside with me. If I get called out on an accident or crime call, it goes with me. For me, it is second nature to pick it up as I leave.