This has definitely been covered before, but I have found that it is sometimes difficult to find what you are looking for in these forums. I would encourage you to seek and find, though.
Regarding OC carry in a car, you will get as many opinions on this as there are posters to this board. There are a number of options to choose from. If you pick any of them - DON"T unload your pistol. NC doesn't distinguish between loaded and unloaded and unloaded does you absolutely no good.
You can put it on your dashboard (I sometimes do this - I have one of those "schticky pads" on the dash - this isn't my preferred method, though)
You can put it on the passenger seat if no one is with you
(These first two options leave the gun unsecured - so in the event of a sudden stop or accident they can go flying)
Strong (rare earth) Magnets - I've heard of people taking magnets and fastening them to a surface and the magnet holds the gun in place (the slide on a semi)
Use the passenger side seat belt to hold a holster that holds your pistol.
Affix some type of holster to a hardpoint, like the dash or someplace visible.
Keep the pistol in your OC holster. Some will say that the seatbelt covers the gun and then its concealed. Others will say hogwash and that they have been pulled over many times and have never had a problem. I know that many cops see it from an intent perspective - the gun is in its holster and the intent is OC, not CC - much like walking up to someone from their left side while the pistol is OC on their right side and not seeing it.
It's as clear as mud. Glad I could help.