After reading a couple different articles recently on the causes of global warming and "greenhouse" gasses, it appears that cars contribute less than 30% of the offensive fumes.  industry seems to be the major culprit.  
  
when will we pour more resources into cleaner manufacturer technologies? why not do as europe does and cap the amount of emissions an industry can contribute? why not change the focus from cars to overall energy consumption and emissions. 
  
**please note: i'm not suggesting we should all run out and get giant SUVs. lower pollution at all possible opportunities**