UX Assessment Protocol for Automotive HMIs: From Real-Vehicle Evaluation to Digital Simulation Environments

This study presents the development and application of a human-centered assessment protocol for in-vehicle Human–Machine Interfaces (HMIs), suitable for real-vehicle evaluation and designed to support future implementation in simulated environments. The objective is to define a structured protocol to assess user experience (UX) in physical testing environments and simulated virtual scenarios. The protocol evaluates user performance and subjective perceptions while interacting with key interface components, including the instrument cluster, central display, steering-wheel controls, and ergonomic adjustment commands, establishing a methodological baseline for future digital and simulation-based evaluations. The work describes the process from requirement analysis to protocol design and user testing, conducted in collaboration with an automotive manufacturer. Participants performed predefined interaction tasks reflecting typical phases of vehicle use. Objective metrics, including task completion times and error rates, were collected alongside subjective evaluations of perceived usability, perceived quality, and satisfaction. Data were analyzed through t-tests and ANOVAs to investigate differences across user groups and interface elements. Beyond the empirical findings, the main contribution of this work lies in delivering a reusable human-centered evaluation framework supporting both current in-vehicle assessments and future simulated environments through automated interaction logging, behavioral tracking, and multimodal data capture while preserving methodological continuity and human-centered validity.