text: Limiting car usage would be beneficial for the environment because the gas wouldn't polute the air. Green house gas emissions from tailpipes polute the air that everyone is breathing. If the car usage was limited, then the air would start to become fresh again. Stated in the passage, "Passenger cars are responsible for 12 percent of greenhouse gas emissions in Europe... and up to 50 percent in some car-intensive areas in the United States." This exerpt from the passage "Car-Free Cities" explains that Europe's percentage is too high and they need to drop it fast or the percentage will grow and the greenhouse gas emissions will increase.