Trust and comprehension are critical for the successful adoption of Automated Driving Systems (ADS). This study empirically investigated how Human-Machine Interface (HMI) design influences user trust across different automation levels. Nine participants experienced three automation levels (3–5) in a driving simulator, with each level implementing different degrees of system proactivity and adaptivity. Quantitative analysis revealed consistently high trust scores (M = 5.31–5.89) with no significant differences between levels (F(2.16) = 1.57, p > 0.05). However, qualitative analysis uncovered critical insights: information overload at intermediate automation, appreciation for transparency, and polarized responses to full automation. Results suggest trust depends less on automation level than on specific interface design choices. Key implications include balancing information provision with cognitive load and ensuring clear control communication. Despite sample size limitations, findings provide empirical indications for user-centered HMI design in automated vehicles .