However, letting your engine idle for more than a minute burns more fuel than turning off the engine and restarting it. Park in the shade. Minimize evaporation of fuel and keep your car cooler in the summer by parking in the shade. Americans rely almost exclusively on the personal automobile for our mobility needs. Unfortunately, the freedom that motor vehicle travel has brought to millions over the past century has also created harmful side effects.
Motor vehicles are a major culprit.
These harmful side effects of transportation burden our society with unacceptable costs to human health, the environment, and our economy. Because the transportation sector relies so heavily on fossil fuels, it is a major source of carbon dioxide and other heat-trapping gases that cause global warming. The movement of goods and people in the United States, for example, accounts for one-third of the nation's carbon dioxide emissions. On a global scale, US transportation alone emits more carbon dioxide than all but three entire countries. Thus, international efforts to cut emissions of heat-trapping gases will need to focus on the US transportation sector for important reductions.