In this paper, we describe the development process of a human-machine interface (HMI) for a purpose-built electric taxi in Singapore. Based on the requirements of taxi drivers and passengers, we developed an automo- tive communication structure to support the connectivi- ty between the vehicle HMI and mobile devices, support taxi-related functionalities and emphasize the charac- teristics of the electric vehicle. We carried out seven requirement studies in Singapore, implemented an integrated HMI platform, and developed different inter- face prototypes for the vehicle HMI and smart devices. This work contributes to the emerging field of automo- tive user interfaces by proposing a fully integrated HMI for an electric taxi.