I stuck a post up like this a while back after I watched 'an inconvenient truth' (carbon footprint, co2 this that and the other. Soon after I watched the other documentary which basically pulled it to bits and showed how co2 FOLLOWS temperature rise (as opposed to our emissions causing it), it then told how one volcanoe would chuck out more Co2 emissions in a day than all our cars, how the COWS (!) cause more Co2 by farting, and most of all how the ocean gives off more Co2!! The whole thing was a big eye opener. I was skeptical to begin with but the more you look at it the more it makes sense. I don't think we should be ransacking natural resources (mazda has a hydrogen rotary engine in testing at the moment :) ), and we need to look after the planet and what lives in it but the Co2 thing seems way off the mark from what I can see.
I also think the disposable nature of modern cars is a lot worse than us driving around in 3ltr sports cars; which are half the capacity of the average car in USA and many other places! My new Zed is my daily drive as its economical compared to my Rx7, and much the same as my old 5 series bmw, also fortunately I don't have to drive to work 2-3 days a week.