Automotive Human-Machine Interaction (HMI) has evolved over decades and has now become one of the most critical components in modern vehicles. This paper introduces the automotive HMI human factors model, designed to provide a deep analysis of the intricate automotive HMI system which encompasses numerous complexities and human factor challenges. The model details the interplay between driving-related and non-driving-related tasks, highlights the diversity of interaction tasks and modalities, and addresses the challenges of integrating software and hardware effectively within automotive systems. Additionally, the paper identifies three significant opportunities that are emerging as a result of rapid technological advancements. These include the development of Artificial Intelligence Generated Content (AIGC) technologies, enhancements in multimodal interaction capabilities, and the progress of autonomous driving technologies. Each of these areas offers potential to vastly improve the functionality and user experience of automotive HMI systems. By using the automotive HMI human factors model, the study not only outlines the existing challenges but also frames the potential for future advancements that could redefine the interaction between drivers and their vehicles.