The German Mobility Panel is a multi-day and multi-period panel survey, which has been collecting data on travel behavior in Germany since 1994. Declining survey participation rates in the last decade in various socio-demographic groups resulted in the implementation of a mixed-mode design for the German Mobility Panel, both in the sampling stage (landline and mobile phone recruitment) and in the data collection stage (paper and web). This study deals with two questions: does the new mixed-mode design affect a person’s willingness to continue participating in the consecutive survey waves? Is there a causal relation between data quality and completeness of survey repeaters and survey mode in the data collection stage? Our results show that survey mode and drop out propensity are not linked but web participants are more likely to switch their survey mode in the consecutive year. Overall, our study makes a case of how adaptations to the survey modes in a longitudinal panel survey on travel behavior affect the survey outcomes.