Please read this:

http://www.emagazine.com/view/?3032

and this: High and Mighty: SUVs--The World's Most Dangerous Vehicles and How They Got That Way

http://www.amazon.com/gp/reader/1586...37#reader-link

It makes more sense to take them off the road than to make them hybrid, hydrogen, biodizel, (nuclear?) ...
If we can not do the first, the second still helps.

Governor Schwarzenegger spoke about the second option here:
http://gov.ca.gov/index.php?/speech/5864/