SLK32AMG makes a bona fide post relating his experiences driving in thick fog. ..... Doubtless he also knows the maxim of driving at a speed where you can see far enough ahead to stop safely.
If he didn't before, he certainly does now. But knowing this maxim is not enough, you have to abide by it. Driving at a speed suitable for the conditions is not rocket science. And making a decision based on what the maximum permitted speed is for the road, or what everyone else is driving at, is a recipe for disaster, as your picture shows - and I have seen far worse than that.
In all. a situation we have all experienced at some time or other.
Really??