It's been awhile since I looked it up since I have a permit and just conceal, but:
Loaded in the glove box in a holster or case is legal.
Loaded sitting on the seat in plain view is legal.
Loaded in a holster NOT concealed is legal.
Not necessarily true.
Without a permit, the gun (when in the car with you) must not be concealed if in a readily operable state. If it's in a holster that covers the trigger guard and has a retention strap, it is not in a readily operable state. If it's only in a friction holster though or has the trigger exposed, it is readily operable.
When in a readily operable state and without a CCW permit, the weapon has to be readily visible for a reasonable observer. This means, if it were in a friction holster on the seat next to you and you were pulled over, the officer wouldn't see it as he came walking up behind your vehicle.
Best bet if you're pulled over is to put your weapon (in its holster) up on the dashboard of your car and keep your hands at 10 and 2 on the wheel.
Or, keep it unloaded and secured with your luggage.