Ok, first things first! I have a truck with two compartments in the door, If I was using either one of them, and not planning to exit the truck, I would do the weak hand thing. If they got to me and were getting me out of the seat I would use my regular hand as I exited. Either way, they might not be aware of what I was doing, IMO.
If I had one of those installed holsters, I would surely have it between the seat and the console, attached either with a bracket that Fobus has for vehicle mounts, or fastened directly to the console. Then I would do the regular hand or strong hand thing, and according to Gun Site Academy, bring it accross the steering wheel top if going to use it out of the drivers door, or take aim and fire direct out the passenger side, or front windshield.
Either way, I would try to get rid of that Blankety blank, seat belt if possible. I know on PD TV they showed gun on hip, and you should loosen seat belt with both hands, remove belt with your left, and draw right handed from belt holster.
It has always been my opinion, as I told my wife when I was going away to the Navy, forty some years ago. If some SOB gets in front of you and tries to force you to stop, hit the gas and see how fast he can jump, if he does not jump too darn bad.
Like they say, the best gun fight is the one you do not have!! And a 3000 lb car is a match for most guys with a gun if your coming right at their kneecaps under full acceleration!!