Philanthropic Engagement and Eco-Friendly Vehicle Purchase Intention in Seoul’s Urban Mobility System: The Moderating Role of Descriptive Social Norms

Understanding the social antecedents of eco-friendly vehicle purchase intentions is essential for advancing the transition toward sustainable urban mobility. From a socio-technical systems perspective, vehicle adoption depends not only on technologies and infrastructure but also on the social contexts in which users make decisions. Drawing on behavioral spillover theory and the theory of normative social behavior (TNSB), this study examines whether philanthropic engagement, namely charitable donation and volunteering, is associated with eco-friendly vehicle purchase intentions, and whether descriptive social norms (measured as perceived compliance with everyday civic rules) moderate these associations. Using weighted binary logistic regression with design-based standard errors and data from the 2024 Seoul Survey (n = 36,280), we found that charitable donation was positively related to purchase intention, whereas volunteering showed no significant overall association in the main-effects model. Descriptive norms moderated both associations: the association of donation was positive and significant at moderate-to-high norm levels, whereas the association of volunteering changed from negative at low norm levels to positive at high norm levels. The findings were robust to alternative specifications, although the norm-conditioned association of donation was concentrated in hybrid vehicle intention. These cross-sectional associations are consistent with cross-domain behavioral spillover and suggest that descriptive norms may constitute an important boundary condition. For urban mobility systems, the results suggest hypotheses, to be tested experimentally and longitudinally, that adoption-oriented policies may benefit from coordination with civic engagement initiatives and from attention to the normative context of everyday social life.