Persuasive messages are commonly used in campaigns promoting sustainable transport to motivate people to reduce private car use. This paper explores the preconditions affecting the motivation of people to reduce private car use when exposed to such messages. A sample of 1100 Swedish residents was analysed for the effect of variables related to accessibility, usual commute mode and attitudes. Significant variables were used to create a precondition index, which was cross-tabulated with demographic variables and stages drawn from the transtheoretical model. The results show that there are differences in the preconditions regarding motivation to reduce private car use between segments of the population. Results indicate that climate morality is the most critical factor affecting motivation, specifically the motivation of persistent drivers. Usual commute mode, car advocacy, health concern, attitudes towards cycling, car identity and travel time also influence motivation. Males, the middle-aged, people with low educational attainment, and rural residents have the least favourable preconditions concerning motivation to reduce private car use.