As cars become more integrated into people’s lives, the design of in-car infotainment systems has become increasingly important. This thesis explores the user experience and Usability design principles of the calling functionality within the infotainment systems of five of the most common cars in Romania. The research examines the design principles that underpin these systems, using the European Statement of Principles on Human-Machine Interface (HMI) as a reference. The primary methodology involved two stages of surveys. The first survey gathered demographic information, car ownership details, and participants' experiences with their infotainment systems. This data was then used to identify the most common cars for the second survey, which further investigated user preferences for different infotainment interfaces. Analysis of the survey results reveals significant patterns in user preferences, with ease of use and convenience emerging as crucial factors in user satisfaction. The study highlights the importance of button placement, interface design, and layout in determining user experience. The most preferred interfaces were those which aligned with HMI principles, emphasizing simplicity, clarity of information, and ease of navigation. Despite certain limitations, such as the small sample size and potential for self-reporting bias, the research provides important insights into user preferences and the impact of design principles on user experience. The findings underscore the need for interface designs that are both user-friendly and align with established HMI guidelines. The implications of these findings extend to the broader fields of Human-Computer Interaction and Automotive User Interfaces, emphasizing the importance of user-centered design in enhancing user experience and satisfaction. Future research could expand upon these findings, exploring the impact of aesthetic design factors and the potential for personalized interface options.