This information is contained in multiple posts on this forum, but here it is again anyway.
Utah Castle Doctrine extends to your motor vehicle. Open carry, or concealed carry of a handgun, condition 1. is permitted. If stopped, it is not necessary to inform the officer, but I highly recommend it.
No carry in UT or Federal Gun Free School Zones (without a permit). No carry in the usual places (Post Office, Federal Building, Court House, Prison, Jails, etc.) No carry on private property that is posted. No carry within a "house of worship" operated by the Church of Jesus Christ of Latter Day Saints (The Mormons).
Semi-automatic pistol = no round in the chamber; loaded magazine is ok.
Double Action Revolver = no round under the hammer or in the next adjacent cylinder hole.