Your AR needs to be within plain sight of any LEO that might look in your car,provided it is not in a case.Your best bet is to not have to rely on the discretion of any officers as to what concealed means.If you were to have it simply lying in the hatch area of your 240 and the glass is tinted,you could be arrested for carrying a concealed weapon along with the great crime called "going armed to the terror of the people" that NC has.Your best bet is to spend $15 on a case and lock.If you had a pickup,it'd be entirely legal to cruise around with it in the gun rack in the back window but it's best to avoid proving that you were legally right in court.I'm not a lawyer and I no longer live in NC,but I do know of people arrested and prosecuted there on gun charges that at least to me seemed pretty spurious so it's best to play it safe - or call your local Sheriff/PD and see what they say.