Wow... this thread is very worrisome... it's one thing to have an occasional LEO that is misguided... it is another thing to hear that their required training is responsible for such ignorance!
Regarding the "?" about storing your firearm in your car... I have a need to occasionally pack to school (because I'm going shooting right after class sometimes)... and, prior to having my permit, I couldn't legally carry it around with me so I would store it in my trunk... I know, a big "no-no" to most, but I did keep it in it's locked container with my trunk fully locked and my car alarm armed. Anyways... I learned that this is legal by finding the following law:
76-10-505.5. Possession of a dangerous weapon, firearm, or sawed-off shotgun on or about school premises -- Penalties.
(1) A person may not possess any dangerous weapon, firearm, or sawed-off shotgun, as those terms are defined in Section 76-10-501, at a place that the person knows, or has reasonable cause to believe, is on or about school premises...
(3) This section does not apply if:...
(d) the possession is:...
(ii) in any vehicle lawfully under the person's control...
Now, this is a little different from the situation mentioned in that I did not have a permit at the time and I was storing the weapon unloaded and locked inside my trunk. But by reading the above law it is clear that you may store your weapon on school property inside your car without restriction (concealed if you are authorized to CC). I have not found any other mention in Utah Law to storing your gun in your car and since I have found no prohibition against it, it seems legal.
I only offer the above code to support the concept that if it isn't illegal, it's legal. I argue that since society typically is less tolerant of weapons on school grounds then this law demonstrates that off of school grounds the same law, or a less-restrictive one, would apply.
As a final support, it should be considered that if storing a firearm in one's car were unconditionally illegal then it would follow that the state would likely have a ban on gun-safes designed for car use, which it certainly does not.
As has been said here many times before...
if it isn't illegal, it's legal.