This is from my limited knolege that i have found on this site and PDO. You can open carry an unloaded weapon (ie. No round in the chamber). With an semi-auto you can have a full mag but nothing in the chamber. Revolvers bceome a little bit more tricky. I have read it be anywhere from the next chamber must be clear or the the one underneith the hamer and the next one must be clear.
Now once you enter your car you must either lock up your weapon or put it somewhere in your car that it isnt accesable to you. I know its a dumb law. I keep mine in a hard case with a lock. If you have a cc permit in any other state, Utah will honor those and you would be excempt from all that i mentiond above.
This is my knolege on this i hope it helps.