Jericho:
Here in OH, as long as it's unloaded, and the magazines (which can be loaded) are stored separately (not necessarily elsewhere in the car - another bag, or side pockets), you're OK.
There are other rules in OH, but they apply more to "in plain sight" storage. Not a good idea unless you're on the way to the range or "field", IMHO.
But this all varies by state, and perhaps even individual localities.
From a pure "spirit of the law" standpoint (and this may not necessarily be a lot of help), any firearm that's stored so you have to do a bit of work to get to it (giving an associated LEO lots of time to react) should be fine, but some states and other localities have goofy rules. Here in OH, until the end of March 2013, magazines had to be unloaded. "Permanent" magazines - like a shotgun tube - had to be unloaded, too. The shotgun tube still has to be, but removable magazines no longer have that problem.
Regards,