This research project examines factors influencing carpooling decisions among Chinese consumers, focusing on motivational messages, default options, trip urgency, past behavior, future intentions, and demographic characteristics. Conducted with 1600 participants, the study found that while scenario sequence and default options did not significantly affect decisions, trip urgency was crucial, with more participants choosing to carpool in non-urgent situations. Societal benefits messaging had the strongest impact on promoting carpooling, compared to personal benefits or safety concerns. Participants choosing to carpool showed higher past carpooling frequency and future intentions. Surprisingly, environmental attitudes did not significantly impact carpooling decisions. These findings offer insights for policymakers and transportation services aiming to promote sustainable transportation options in China.