I keep one in my door pocket within reach of left hand when driving, one between the seat and console for my right hand, one under the passenger seat in case I'm sitting over there, one in each seatback pocket (because sometimes I vacuum out the back seats and I need to be protected), one in the cargo cover net if I'm in loading stuff in the back of the car, and then of course one in the engine bay and tucked up above the subframe for when I'm working on the car.
Better safe than sorry, it's a lot easier than trying to reach my ankle holster, IWB holster, or the gun up my ass while driving.