One person drives 60,000 miles in a car that averages 30 miles per gallon (mpg), while another person drives 60,000 miles in a car that averages 20 mpg. Over the course of the 60,000 miles, how many fewer pounds of CO2 are released by the 30 mpg car than by the 20 mpg car?

20000 pounds

Explanation:

Generally 1 gallon of fuel burnt gives of 20 pounds of CO₂

Difference in the gallons of fuel burnt

The 20 mpg car burns 1000 gallons of fuel more than the 30 mpg car

The amount of CO₂ would be

The fewer pounds that the 30 mpg car would release is 20000 pounds