CO2 emissions reduction has long been discussed, since the problem is one of the most urgent issues we human beings are faced with in the 21st century. Time-sharing electric vehicles (TSEVs), combining the benefits of cleaner energy and more sufficient utilization, are considered a sustainable future transportation tool, with increasing support from governments around the world. Although numerous studies have been carried out in this domain, few have studied the development process, considering the inverse interrelations, including the policy implementation effects and user choice, in a dynamic way. This research fills the previous academic gap and presents a system dynamics (SD) model incorporating scenario analysis to simulate the effect of introducing time-sharing electric vehicles in changing the user quantities in transportation tools, including public and private sectors, under different levels of government subsidies, thus providing policy implications and ex-ante assessment for the subsidies. The results suggest that it is not the greater the subsidy, the better the effect. Considering that one of the purposes of introducing TSEVs is to reduce private vehicles, there is a threshold for user transfer. It is actually under low subsidy that private internal combustion engine vehicle (ICV) users are most attracted to the TSEVs compared to the medium and high ones. The gap between the simulation results and common sense reminds us that ex-ante assessment and overall planning in the process of industry development are necessary.