This research delves into the transformative potential of self-driving vehicles by investigating their impact on passengers’ happiness. As autonomous transportation technology rapidly evolves, understanding the user experience within these vehicles becomes essential. To investigate the happiness of the self-driving vehicles’ passengers, which is defined as positive emotions and cognitive well-being during self-driving rides, real-traffic test rides were conducted among 31 participants, companied with two before-ride and after-ride surveys. The study employs a comprehensive approach, combining self-reported survey data and biometric measurements, which includes the participants’ heart rate and the eye movement, to investigate passengers' happiness. The results present an overall positive emotions and positive attitudes towards the self-driving vehicle. Moreover, the findings present a notable shift in passengers' attitudes, with originally neutral sentiments transitioning to positive perceptions following the test ride. Participants exhibited various activities during the ride, enhanced comfort with the concept, and an improved satisfaction with self-driving technology. Remarkably, statistical trends suggest that self-driving vehicles hold the potential to alleviate stress and optimize time management, positively impacting passengers' overall well-being. Furthermore, biometric data of the participants presented participants’ different physical reaction on different traffic scenarios and indicated the happiness and well-being of the participant. The research emphasizes the broad implications of self-driving technology on individual happiness, concerning both emotions and attitudes, extending beyond functional enhancements to encompass passenger happiness and societal integration.