Interesting find I came across. A random video on my facebook feed sent me to google, searching "CO2 emissions by cars." The top result was a paragraph from epa.gov, which claims that "every gallon of gasoline burned creates about 8,887 grams of CO2." Could the oxygen binding with carbon monoxide and other molecules/elements when gas is burned create that much of a difference in it's weight? Because 8887 grams, divided by 454 grams (1 lb), equals 19.5 pounds. I know a gallon of gas doesn't weight almost 20 lbs, and it seems unlikely that the addition of oxygen would not fully account for the additional weight, but maybe I'm wrong. Can you guys help me understand this better?