I use a cross-draw OWB almost all the time (although a shoulder holster works well for the same reasons that I find comfortable). I find it easy to draw in the car. When I sit down, I pull up my shirt, sweater, or jacket to expose my gun, fasten my seat belt, and I'm good to go. Someone at my window would never notice it. I can quickly pull down my shirt, sweater, or jacket to cover it before I leave the car.
I prefer my gun on me. Sometimes I will drive in certain parts of town where I have another gun under a jacket in the passenger seat with the butt towards me. It might be a J-Frame or even a FEG High-Power clone, but it too goes with me when I leave the car. The J-Frame goes in a pocket, the FEG into a strong side holster. I don't leave my guns in the car.
I can understand why you might want a car holster, but I find several problems with them. Their visibility, anyone else in the car has access, and if you have a wreck where is the gun?
Consider a cross-draw; much easier than any other way to present a gun in a car for right-handers without contortions.