## 5 Discussion  
Based on the results obtained from the tests conducted and the data collected, as well as considering the current state of the art, we observed that some users encountered challenges while utilizing both proposed interfaces. However, it is essential to note that a significant level of user engagement accompanied these difficulties. As anticipated in the introduction, one of the main areas of concern about certain aspects of the graphical user interface led to users' confusion, resulting in the access of unnecessary interface parts that were not essential for completing tasks. Nonetheless, the impact of this issue on overall performance was not substantial. The efficiency and intuitiveness of the proposed interaction compensated for the additional menu navigation, which has been previously corroboratedby several studies [9; 15; 20]. These findings further reinforce the notion that touchless and non-touchless interactions are comparable regarding usability and distraction.  
However, the perceived physical fatigue divergence between the two interaction methods was a notable distinction. The touchless interaction was more tiring, likely attributed to the specific prototype employed in the experiment. The practical and developmental constraints compelled users to maintain a particular hand and wrist position throughout the study, a factor also highlighted by [PERSON] et al. [10]. Despite the increased physical strain, this did not adversely affect the attractiveness of the technology. Indeed, users found the touchless interface more user-friendly and perceived it as a premium feature with a better user experience.  
Participants similarly evaluated the workload, performance, and interaction experience of both devices. Even though they had varying prior experiences in different fields, only one participant had used the trackpad in a vehicle. Therefore, it can be concluded that both devices are new to the automotive sector, and previous experiences do not affect first-time interaction in this context. As a result, both devices can be effectively used in the automotive field.  
These findings underscore the significance of considering usability and physical implications when designing touchless interfaces. At the same time, there may be a trade-off regarding physical fatigue; the enhanced user-friendliness and perceived value of touchless interactions contribute to an overall positive user experience. These considerations may be limited by the small sample size, which could affect their applicability to a broader population. A within-subject test design could have increased the results' reliability. However, in preliminary pilot tests, participants found the overall test duration of about 2 h too long, making this option unviable.  
To optimize this technology, further research and development efforts should prioritize refining ergonomics and addressing the physical demands of touchless interaction. Including more eye movement indicators or participant takeover performance could improve the meaningfulness of the results. Striving for a balance between usability and user comfort will ultimately enhance the acceptance and desirability of these interfaces.