This manuscript presents the results of the application of an extended norm activation model to the explanation of car use on the way to the university with a sample of 430 students of 3 German universities. The proposed two-stage structural model is supported by the data. First, a norm activation process starting with awareness of consequences activates subjective and personal norms. Second, behavior is determined by car-use habits, perceived behavioral control (PBC), car access, and effort to use public transportation. The influence of personal norms on behavior is mediated by habits. Subgroup analyses of the second stage of the model show a high structural stability, but differences in the regression weights.