Someone over on the Bicycle Culture channel of Google+ highlighted this little study which quantifies the degree to which cars want to kill you.
I’m kidding (sort of).
What the study shows is that unless you wear a bright yellow vest with a sign saying you are recording the drivers in your vicinity, you will almost always be passed too damn close. Actually, the study showed that even then there are drivers who will pass within 50cm regardless of your clothing.
What this tells us is that there is a chronic failure on the part of drivers in the UK to acknowledge that they share the road with other human beings. It seems unlikely the situation is much better here in North America.
Regardless, if you share the road with cars, you need to pay attention to the recommendations at the end of the study:
… it is suggested that infrastructural, educational or legal measures are more promising for preventing drivers from passing extremely close to bicyclists.