Hybrid electric vehicles (HEVs) can significantly contribute to sustainable road transport, yet driver behavior has a marked effect on actual energy efficiency (i.e., the ultimate sustainability effect). The objective of the present research was to examine ecodriving motivation of HEV drivers. To this end, we recruited 39 HEV drivers with above-average fuel efficiencies (suggesting at least some degree of ecodriving motivation) and collected interview data, questionnaire responses, and fuel efficiency data. Specifically, we assessed factors that motivated drivers to drive energy efficiently as well as factors that led to reduced ecodriving behavior. Ecodriving motivation of HEV drivers was found to be particularly driven by the goals of environmental protection, cost reduction, and gamification aspects. Furthermore, relationships between drivers’ most important ecodriving motivation and the level of ecodriving motivation, the achieved fuel efficiency, the level of total HEV driving experience, as well as typical HEV driving distances were examined.