The rules of the road

It's quite some time since I took my driving test and I've come to realise that my recollection of some of the rules of the road is somewhat sketchy. While the basics are clear, how many of us can remember the finer points of the Highway Code?
In some senses we might feel that we never have more knowledge than the day that we pass our driving test. On that day we probably know the Highway Code as well as we will ever do in the future.
We've probably spent some hours learning the rules of the road - making sure that we remember them so that we can be allowed to drive on UK roads.
After the test, our knowledge probably gradually falls away. Sure, there are some aspects of what we have read and taken the time to learn that will always stay with us. But how many of us remember the finer points of the test?
How many of us would know, for instance, at what level of visibility we should turn on our fog lights? Or how about the rules governing the use of motorcycles?
Some would undoubtedly respond that this lack of knowledge is countered by an increase in experience. We may not know the exact wording of the law, but our experience of driving means that we are much more able to deal with most situations than we were in the early days.
I started to think about this subject after a recent visit to Italy, where many people seemed to be using scooters and smaller motorcycles.
I was surprised by how few people were wearing motorcycle crash helmets - it was certainly very different from what we see in the UK.
It's clear that laws vary from country to country, but I wonder how much we all really know about the regulations in our own countries?
Knowing the rules of the road is vital for all of us - how much do you know?