A signage system (10) including one or more visual display devices (11), each mounted for display behind the windshield (15) of one or more parked and ignition-off vehicles (16). Each sign (11) has a visual display surface (12) that is capable of forming an illuminated graphic display (13) on the visual display surface (12). The visual display surface (12) would be visible to observers in front of the vehicle (16). The system (10) includes wireless communication hardware (60) that allows the visual display (11) to be programmed by a remote programming device (41). Each of the display devices (11) can be programmed to have a separate message and each message would scroll from left to right across the display surface (12) in a time coordinated manner so that the message appears to scroll consistently from left to right across the visual field of the plurality of display surfaces (12).