Everyone except folks doing true investigation are legally required to be in cars marked at least minimally - up to and including the chief (or the mayor, for that matter). 186.067b Publicly owned vehicles, how marked -- Exceptions. (1) All publicly owned vehicles shall be properly identified by an insignia on one (1) door on each side of every such vehicle. (2) Such insignia shall not be less than twelve (12) inches in width and not less than twenty-one (21) inches in length, of a design so chosen