Car ownership is the primary driver of car use, which in turn is the leading contributor to passenger transport sector emissions. Hence, understanding the key determinants of car ownership is crucial to designing a policy framework that will effectively reduce emissions. Based on a 2022 German mobility survey, this study utilizes multinomial logit models to analyse a range of influences on car ownership including socio-demographic and infrastructural factors, respondents’ stated policy responses, and their motives for car ownership. We find that car ownership increases with an individual’s age, income, the share of social contacts owning cars and with smaller towns of residence. Habits, measured as the number of years already spent as a car owner or non-owner emerges as a dominant factor. Our three main insights include: First, car ownership in rural Germany is particularly high and can be effectively reduced by public transport supply measures. Second, situations of radical change—when individuals overcome the force of routine to reflect on their car ownership status – present unique opportunities for policy intervention. And third, isolated or mild policy interventions may only have a limited impact. To significantly influence car ownership levels, policies will likely have to be very stringent.