text: In opposition, to these efforts, automobiles are usually an important factor to the suburbs where usually middle-class people live. This causes a huge impediment to current efforts to significally reduce greenhous gas emissions from passenger cars. In Europe,passenger cars are the reason for the 12 percent of greenhouse gas emissions; in the United states that number almost quadriples in size in some car-intensive areas. The approach is to make suburbs more compact rather than having malls on the border on distant highways.