Travelers commit themselves to particular behaviors through the ownership of cars and season tickets. They trade a large one-time payment for a low or zero marginal cost at the point of use. It can be assumed that these commitments influence travel behavior and future commitment situations. Apparently, none of the literature addresses the choice between the commitment to one or the other mode and its impacts on travel behavior as well as the temporal dimension. Models that use structural equation modeling to test a priori hypotheses on the paths linking car availability, ownership of a season ticket for public transportation, and modal usage during three different time periods are presented. Modal usage is operationalized as the number of trips by car and public transport. The models are based on two different panel surveys (in Germany and the Netherlands). The results show that there is a high degree of stability in car ownership and a relatively high degree of stability in season ticket ownership (for Germany only). The commitments influence modal usage, whereby the influence on one mode is higher than the influence on the other mode. The relationship between the two modes is a substitutive one.