This study explains sharing economy platform usage intention. The results of PLS-SEM estimations based on survey data (N=655) in the context of non-profit carpooling indicate that sharing orientation (i.e. sharing usage instead of owning/buying), grassroots engagement (i.e. non-profit organization driven by volunteers), and platform authenticity (i.e. loyalty to the original carpooling practice) are strong determinants of people’s attitudes towards the carpooling platform while trend orientation (e.g., the “sharing economy” paradigm) is not significant. While digitalization can optimize older practices (e.g., hitchhiking), online platforms facilitating contemporary practices (e.g., carpooling) need to be embedded in the original sharing ethos and values to raise usage intention.