"Passenger cars are responsible for 12 percent of greenhouse gas emissions in Europe...and up to 50 percent in some carintensive areas in the United States." emphasis on original That many emissionsarehorrible for the environment and even worse for our pockets, because they're just going up in smoke.New citiesare rising and are acctuly trying to adopt this trend by making cities denser, which means that all the stores and your work place are in walking distance.