Metropolitan city planning and development including advanced transportation infrastructures have caused to increase the separation of working and living spaces. This separation dramatically increases commuting population throughout metropolitan areas. Moreover, many commuters prefer to drive cars which generate much more transportation costs and air emissions than public transportation options such as bus and subway. Seoul in South Korea is not an exception for this challenge. Recently most of the people agree that air emissions including carbon dioxide are the significant factor for climate change. It brings about a lot of social, economic, and environmental issues, which force to legislate the environmental policies and regulations to reduce air emissions. In this study, we analyzed the commuting pattern, size, and distance of 79 counties around Seoul to evaluate the implications of eco-friendly car technologies and transportation policies for carbon reductions. Our results show that the gross annual carbon emissions of commuting cars would be reduced from 4,150 to 3,163 thousand metric tons between 2005 and 2035 in spite of the growth of the ratio of car commuters through improving fuel efficiency. We could expect that regional government support for the propagation of eco-friendly cars is the most effective way to reduce carbon emissions for commuters.