The promotion of electric vehicles (EVs) in the transport sector is critical to achieve the urban sustainable goals, while the EV diffusion process varies in different cities mainly due to regional heterogeneities in consumer preferences. This research intends to reveal the EV consumer heterogeneities in the city level by applying conjoint analysis on the survey data from 1251 questionnaires collected in twelve EV promoting cities of China, and tries to simulate the possible EV diffusion process in the twelve cities by further constructing a system dynamic model. Through the study, it is found that the investigated cities could be categorized into three types from the perspective of consumer EV preference, which includes performance-driven, social-driven, and privilege policy-driven EV promoting cities. In addition, the demand heterogeneities may result in differentiated urban EV diffusion processes, which could be clustered into natural diffusion independent of policy, fast diffusion depending on appropriate policy, and lagged diffusion insensitive to policy. Based on our analysis, policy suggestions are put forward for accelerating EV diffusion in different types of cities respectively.