This thesis investigates how a Mixed Reality Conversational Intelligent Agent Companion in Cars (MRCIAC) can enhance the travel experience of individuals in unfamiliar cities by addressing four main problems: difficulty finding popular locations, lack of a travel buddy, complex in-car human-machine interaction, and neglecting passenger experience. The research approach includes three methodologies: Research Through Design (RTD), Prototype Iteration, and Descriptive Design Evaluation. The study creates and evaluates three types of prototypes, including mobile applications, Virtual Reality (VR) and Mixed Reality (MR), to demonstrate the potential of mixed reality intelligent agents to revolutionize human-computer interaction in transportation and improve the travel experience. The outcomes of this research demonstrate the potential of MRCIAC to provide a companion for the owner and passengers on a trip. It is hoped that further research in this area will lead to exciting new developments and improvements in transportation.