Dave though cars do polute and add to the carbon load on the environment, they certainly aren't the only problem or the vast majority. I think you have to look at industrialization, and big countries like China relying heavily on coal burning for heat. It's also a balance of resources that can recycle if you will, those carbon emmisions such as trees and algal beds in the oceans. It's fuuny because everybody is quick to defend rain forest preservation and will tell you that rain forests are needed to recycle co2 emissions out of the atmosphere, and this is true but not to the numbers they would lead you to believe.
They real place to protect is the oceans. Phytoplankton eat co2 and produce o2. To the tune of something like 85% of the o2 we enjoy(if I remember correctly from school 20 years ago!) What is a lot more worrisome to me than fossil burning vehicles, is chemical runoff from various sources including agriculture, and industrial waste which goes into the rivers and streams and eventually into the oceans where it does a great job of killing plankton. Add to this south east asian aqua farming of high density shrimp farms where the waste causes agal blooms that kill reefs and then the whole area goes anoxic,(coral reefs are also a source of o2, and once the algal bloom dies so does everything else) and well now your talking a big problem! When I lived in the Keys( as a marine biologist) I remember the average land elevation is something like 3-4 ft above sea level. What is being seen by the melting at the caps, is a slow rise in sea level of about 1 inch per year. So yes in about 30 -40 years there may be no Florida Keys.
I think what ever anyone can do to lower their personal impact on the environment is all we can do, and I'm willing to get a more effiecient car to go to work when I buy my next car, but I really don't think hot rodders are the problem here, I think it's this ideal that the earth is indestructable and therefore we don't need to do anything different. That and the fact that all the alternative energy resources are more expensive, and limited in production at the moment. Plus we all are not getting any richer in this economy! Our heating bill shot to 400.00 bucks for a 2300 square foot house in a relatively warm area! Our thermostat was set to 64. The house is 2x6 framed with dual pane windows. Our problem was no window coverings, so out went the criedit card for insulted drapes and blinds! What a difference that just made. Hopefully the bill will be a lot less next month! Little things make a big difference!