Here's how they do it in a W124 Mercedes. Could be inserted into other washer bottles, and plumbed from the throttle body return line. May not be needed, with modern fluid. Guess Autobahn use at speeds exceeding the Disco flying brick limits could have extra windchill.

Or it could be part of a mobile moonshine operation (you wondered where MMO came from)....

 

wow, fancy. my disco keeps it simple. i have the under bonnet high temp, slow dissipation edition. it manages to keep my fluid nice and toasty.

 

http://prestone.com/sites/default/p/...ls/de_icer.jpg

Done.

 

Maybe it could be a way to make hot water for tea enroute....

 

On my classic one of the heater hoses runs thru the washer bottle. I just found an electric one in my basement this weekend must have come from JC Whitney or some place. looks like a fuel filter with 2 wires.