Back when I was in the service in Germany in the mid 80's I saw a plethora of these third tail lights on all manner of vehicles and trucks. Some even had separate housings. (I think that may be where Lizzy Dole got the third brake light idea.) They were only used in the foggy times of year and they were quite effective IMHO. Huge multi-car wrecks were common on the autobahn when people drove down into a foggy valley at break neck speeds and slammed into a developing mess. Being able to see those tail lights a little further out than normal saved some lives in my opinion.

My 1985 244Gl has the switch near the headlight switch. But I have never been able to get the darn thing to work, yet.