This paper explores and analyses how to reduce smog-related air pollutants and carbon dioxide emissions generated by passenger transport systems in Beijing. In-depth surveys with experts and practitioners in China are used to examine the current business-as-usual projection for emissions in Beijing, the drivers and trends affecting current projections, and to develop alternative scenarios that might help reduce projected emissions significantly. These are based around different variants of population and migration growth and environmental stewardship. Current levels of smog caused by transport emissions are much higher in Beijing than internationally accepted safety standards, partly because of high levels of motorised traffic. Carbon dioxide emissions always tend to be overlooked because economic growth is prioritised. The sustainable model represents one of the best models for Beijing to follow; however, Beijing faces major challenges in becoming more environmentally sustainable over the next few years, mainly due to population growth and increased migration, even if there is powerful top-down government environmental stewardship. The aspiration to reduce smog-related air pollutants and carbon dioxide emissions in Beijing by implementing sustainable transport mitigation measures seems very ambitious; however, it is perhaps in this context that the real innovations in transport planning will emerge.