How does fuel economy correlate with carbon dioxide/GHG emissions?
Every gallon of pure gasoline combusted produces approximately 20 pounds of carbon dioxide, assuming that perfect combustion occurs. One gallon on gas weighs approximately 6.30 pounds, and gasoline is composed of about 87-percent carbon and 13-percent hydrogen, by weight. As such, the carbon in each gallon weighs 5.48 pounds. When gasoline is mixed with air and burns, carbon (from gas) combines with oxygen (from air) to form carbon dioxide (CO2). Hydrogen (from gas) combines with oxygen (from air) to form water (H2O). The atomic weight of each carbon atom is 12, while the atomic weight of each oxygen atom is 16. Therefore, each CO2 molecule weighs 44 atomically (12+16+16). Therefore, if every one atom of carbon (12) produces one molecule of CO2 (44), then calculating the weight of CO2 produced by a given quantity of carbon requires multiplying the weight of that carbon by 3.67 (or 44 divided by 12). The carbon in one gallon of gas (5.48 lbs.) times 3.67 equals 20.11 pounds. Sometimes c
