<p>Due to demographic changes and economic growth, analyzing the impact of sociodemographic changes on travel demand is essential for transportation management and planning. Using Taiwanese data from the years 2008 and 2018, this study investigated the influence of sociodemographic factors on car use by employing age–period–cohort analysis. Blinder-Oaxaca decomposition was further employed to assess the relative importance of these factors in contributing to changes in travel mobility. Travel mobility can be captured by weekly driving days, daily trip time, and monthly fuel expenditure. The results show that the peak car phenomenon has not occurred in Taiwan, as the number of driving days, daily trip time, and fuel expenditure all rose between 2008 and 2018. Although population aging may lead to a reduction in car use, this is offset by the increasing car use of the younger generation. Commuting and business trips were major factors in increasing car use during the study period, and younger cohorts exhibited relatively high travel mobility, with more car driving days and fuel expenditure than older cohorts. The policy implication is that commuters and younger drivers should be targeted by policymakers seeking to promote green mobility. Transportation planners should not only consider the travel behavior of different groups but also understand the changes in travel mobility related to society’s demographic structure.</p>