Volume calculation of one ton CO2
One ton = 1000kg
One cubic meter = 1000liters
One mole CO2 = 44.0g     (CO2 = 12.0g + 32.0g = 44.0g)
One ton contains 22730 moles of CO2    (1,000,000g / 44.0g/mole)
One mole is 24.47L     (Boyle's law at 25°C and 1 atmosphere pressure)
Volume of one ton CO2 = 22730moles × 24.47L/mole = 556200L = 556.2m³
One ton of CO2 occupies 556.2m³ of volume.

Height of CO2 on US land surface
US 1997 CO2 production = 5,456,000,000ton
US volume of CO2 production = 5,456,000,000ton × 556.2m³/ton = 3,035,000,000,000m³
US land surface area 9,158,960km²
Height of CO2 on US land surface = CO2 volume / surface area = 3,035,000,000,000m³ /     9,158,960km²= 33.14cm (about 1.1 feet high)
Every year the United States emits a 33.14cm high blanket of carbon dioxide over its land area.

Volume CO2 from one gallon of conventional gasoline
Gasoline density = 2791grams/gallon
Percent carbon by mass = 85.5%
Mass of CO2 from 1 gal of gas = 2.791kg/gal × 85.5% × (44.0g CO2 / 12.0g C) = 8.750kg
Volume of CO2 from one gallon of gas = 0.008750ton × 556.2m³/ton = 4.867m³
The combustion of each gallon of conventional gasoline produces 4.867m³ or 171.88ft³ of CO2.

CO2 and the Washington Monument
Volume of the Washington Monument = 22026ft³ = 623.7m³
Gallons of gasoline needed to fill the Washington Monument with CO2 = 623.7m³ / (4.867m³/gallon) =     128 gallons
The New Beetle can run about 4000 miles on 128 gallons.
A New Beetle, driving 12,000 miles, will create enough CO2 emissions to fill up the Washington Monument three times

CO2 emission data from USEPA and land area data from CIA