I,ve been driving MB for over 40 yrs Europe and in the USA Fog lts. always stayed on no mattrer ..high or low beams....they switch Indepent.......American Mfg,s are now putting Driving (white ) Lights on thier Cars...Some may call them FOG Lts. But Real FOG lights are Amber or as we call them orange. The FAA sets standards for Aircraft lights ...The following colors that can be seen the furthest in Fog conditions GREEN IS #1 ..Amber Is #2 .since green would be confusing to approaching Motorists in Foggy conditions.(on the ground ) They decided to use Amber......The reflection of either green or amber off of FOG is less than White........White has the Advantage Low to the Ground where it can shoot under the fog....That is why they are ony classified as Driving Lights.........DO wish some of the american car mfg. would aim those lights(set standard aiming limits) some of them are really blinding .because they are not aimed properly............. The reson that Airport Rotating Beacon Light is green ,Is as I mentioner earlier "Green is the Best in FOG.".. Just my 2 Cents.....Pete