One gallon of gas

Burning 1 Gallon of Gasoline Produces 20 Pounds of CO2.
One of the major culprits in CO2 pollution is the automobile. You may be surprised to learn how much pollution is produced when you drive your car. For every gallon of gasoline you burn in your car, you remove 21 pounds of breathable Oxygen from the atmosphere, as well as adding 20 pounds of CO2, or Carbon Dioxide to the atmosphere. This might seem unlikely or improbable, but it is a fact.
A gallon of gasoline weighs 6.3 pounds and is comprised of 87% Carbon (C) and 13% Hydrogen (H). When you burn gasoline, a chemical reaction occurs, using Oxygen from the atmosphere. The Hydrogen and the Carbon separate, then recombine with Oxygen from the atmosphere to form H2O, or water, and CO2, or Carbon dioxide.
EPA calculation page
When you multiply that 21 pounds by the United States daily consumption of gasoline (378 million gallons), the result is 7.9 Billion pounds of Oxygen that we are removing from the atmosphere and converting into 7.5 Billion pounds of CO2 each and every day of the year.
Today, I rode my bicycle to the bank, the office supply store and Radio Shack. If I had driven a car, I would have used a gallon of gas. But I rode my bicycle, got some exercise and saw a humming bird fly right near me as I rode along the sidewalk.