In addition to my carry piece, I have another in a fobus-type mounted to the underside of the dashboard accesible via the glove compartment. Pop open the glovebox, reach up, and you are armed.
Some advantages I see to this method are that I don't have to constantly remove the pistol from the car as I would if it were located between the seats, etc. Also, should the car be stolen, there is a chance that the thief would not spot the pistol. Finally, passengers are blissfully unaware that they are 3 feet from a handgun (my family -except for my wife- does not know I have a CHL).