Have enjoyed this feature on European cars for years. On my 50's/60's Renaults and Mercedes there were dedicated(in addition to the parking lights), low wattage bulbs for this function and they were intended to be left on all night. On our 2000 BMW and on our CS it seems the regular parking lights are activated for this function and leaving them on all night could drain the battery.

The concept of a dark, narrow street in a continental village, where one might park, on either side of the road, and it would serve a real purpose to have a light on, on the traffic side only, has always had an appeal for me. To have retained this feature on "export" cars, without the low current drain circuits seems archaic. We park only in well-lighted, marked and designated spaces, right? And never all night, right? Unless we are home with our car in our own 4-car garage, right? Right.

Also, don't confuse the rear fog light with the left/right parking lights. The parking lights are normal, white in front, red in rear lights, like parking lights except only left or right can be activated (by the turn signal stalk with key off). The fog light is a dedicated, brighter-than-normal tail light, left side only, for increased safety in rain/fog conditions. Mine gave a certain peace of mind on the Autobahn at 120 mph in the rain while being passed by other cars going faster.