Depending on the workplace rules in effect where you work you vehicle may be subject to search by the company or its chosen representative at the time. You can refuse the search but will probably be terminated.When you drive into a parking lot in your personal vehicle, does the right to control the interior of your personal vehicle automatically transfer from you to the parking lot owner who has no vested interest in your personal property which remains inside the body of your personal vehicle?
Everyone needs to read the rules where they work.
Michael