Emissions from the transport sector represent the fastest growing source of greenhouse gas emissions. There is little prospect that this situation will be resolved with a single technological fix. As developing nations quickly move to catch up with the motorization levels of developed nations, the sheer number of private vehicles may overwhelm any advances made by cleaner fuels. By 2030, there is projected to be more vehicles in the developing world than in developed nations. Despite the growth in developingâ€nation transport emissions, the sector has produced relatively few mitigation projects within the mechanisms of the Kyoto Protocol. However, a few developing cities, such as Bogota, Colombia, have demonstrated innovation in lowâ€cost solutions to reducing emissions. This research employs scenario analysis to examine the size and cost of potential emission reduction options from the urban transport sector of developing nations. In particular, the analysis compares the cost of greenhouse gas emission reductions from fuel technology options to reductions from measures promoting mode shifting. This comparative analysis indicates that a diversified package of measures with an emphasis on mode shifting is likely to be the most costâ€effective means to greenhouse gas emission reductions.