Here are two interesting web sites that pretain to our discussion.
The first shows greenhouse gas per capita for the United States (sadly again, no data like this for Canada yet). Until you zoom in you dont see that the center cities perform best while the further out you go from the center of any major city it gets worse and worse.
Make sure to find a city and zoom in.
The second one shows our region and reveals commuting patterns to work. The take home message from these is that most people are not commuting to downtown Vancouver from the so called "suburbs". They are commuting in many directions and very often half or more people live and work in the same town. This is not true everywhere. Calgary, for example, has a very different pattern where a much higher percentage of area workers work in downtown Calgary, commuting in every day.