(a) No person shall drive any vehicle upon a highway with any sign, poster or other nontransparent material upon the front windshield, side wings or side or rear window of such motor vehicle, other than a certificate or other paper required to be so displayed by law.
(b) No person shall drive upon a highway a vehicle with a removable windshield placard issued pursuant to § 2135 of this title or pursuant to a similar statute of any other state or country hanging from or attached to the vehicle's front windshield rearview mirror. A person may be found guilty of violating this subsection whether or not the placard is valid.