* Fuel efficiency of your car in miles per gallon (MPG)
* Number of miles you drive in a year
* CO2 emissions per gallon of gasoline (lbs CO2/gallon)
Once you have this information, you can calculate the amount of CO2 produced by your car using the following formula:
CO2 emissions (lbs) = (Number of miles driven / MPG) * CO2 emissions per gallon of gasoline
For example, let's say your car gets 25 MPG and you drive 12,000 miles in a year. If the combustion of each gallon of gasoline produces 22 lbs of CO2, then the amount of CO2 produced by your car in a year can be calculated as follows:
CO2 emissions (lbs) = (12,000 miles / 25 MPG) * 22 lbs CO2/gallon = 10,560 lbs CO2
Therefore, your car produces 10,560 lbs of CO2 in a year.