Ergonomically, a 9mm pistol tucked in the back of your waistband is both uncomfortable and awkward to access, especially with a latched seat belt.
The best place for easy access is where your gun hand naturally rests. If it's your crotch, you'll want it nearby.
Seriously, the area around the handbrake falls most naturally for most people. You could have a holster velcroed to a bracket next to the driver seat. When leaving, remove gun and holster and take it with you. Cover it with a towel or magazine so it doesn't alarm passengers or passersby.
Not sure you'd want to drive your 911 in those areas anyway. Sorta like walking down a dark alley with bills hanging out of your pocket with a sawed-off shot gun under your trench coat.
Sherwood