Didn't recall Imperial having that option. My uncle bought a '71 Sport Fury used. It had that option on it. Other cars had "head light washers", which was just a spray nozzle on the headlights (as Mercedes) on non-hidden headlights. Chrysler put the brushes with it for greater effectiveness. Got the scum/film off with the brushes. Up north, it was probably more about snow and such, in TX it was more about road film/scum buildup on the headlight lens. Plus a thin layer of sand residue, too.
This is ONE of the options you don't want to add on later. Lots of stuff to change/modify involved. The switch could probably be relocated somewhere, but still lots of things to change or add. In the same category, in that respect, as the Dodge SuperLite.
CBODY67