I can't answer this question but this should be a manditory safety feature in the US. Not only do I find it more useful than front foglights but I always turn it on in heavy rain so people behind me can see me.

Of course, those civil servants in Washington are the same dorks who made Mercedes put sealed beam headlights on my '84 190D and can't understand that frontal offset crashes are far more likely than frontal crashes.

...end of rant.