Check this link which a google search turned up:
http://www.usctcgateway.gov/tool/
It shows 1000 lbs of carbon equivalent to 189 gallons of gasoline or 5.29 lbs carbon per gallon. Figuring a compact car at 30 mpg, that's about 0.18 lbs carbon per mile. (This is carbon, not carbon dioxide). Double that for a big pickup, 2/3 or half that for little hybrid.