The Dude

I try and look up different states laws when I travel. I went to Texas once and couldnt find any clear laws all in one space so I just kept te magazine in the trunk and the firearm in my console. I know they do have to be seperate in a lot of states. Texas only legalized open carry a couple months ago from what I understand.
In Louisiana your car is considered an extension of your home so you are good to go no matter how you carry when in your car.

SloMotion

Yep, they got those reciprocal agreements between states, here's the link I use to try and get an idea of who accepts what:

Concealed Carry Permit Reciprocity Maps - USA Carry

Always good to check. IL, OR, CA, NV, NY, a few other New England states & HI seem to be the main ones that don't practice some kind of reciprocity.

I have never heard that a car is considered to be an extension of your home before this thread ... interesting concept and a good example of how gun laws can vary between states, IMO. It's why I tell people, if you're gonna' carry, get a hold of the local laws and read, read, read and clarify if there's something you don't understand ... it could save you a big headache down the road, .