I have a CPL here in MI, and at least in my state you have to have your long gun unloaded and cased in a vehical. I just cant see the reason to have a shot gun in a "hiding spot" in your SUV thats all. I'm sure that if you were to get pulled over and you told the cop you had a shotgun in a "hiding spot" in your car they might have some more questions for you.
Dont get me wrong I am all for the 2nd amendment and the constitution, I just dont under stand why someone would want to carry a hidden shot gun or 1,000 rounds of ammo in thier vehicle. I dont go around looking for a fire fight, but it seems like some people plan on it.