Because the gasoline used by motor vehicles is refined from petroleum, and the refining process produces large volumes of carbon dioxide, reducing carbon dioxide emissions requires reduction in motor vehicle usage and increasing the energy efficiency of vehicles.
由於車輛使用的汽油提煉自石油，而提煉過程中會大量釋放出二氧化碳，因此要減少二氧化碳，就須降低車輛的使用和提高運輸工具的能源效率。