Subdivision 18-a of section 375 of the Vehicle and Traffic Law requires that every motor vehicle registered in this State and manufactured or assembled after June 30, 1965, and designated as a 1966 or subsequent year model, shall be equipped with a vehicular traffic hazard warning device approved by the commissioner. For the purposes of this Part, such a device shall be a separate, driver controlled unit which causes the front and rear directional signals to flash simultaneously as a vehicular traffic hazard warning.