Transport accessibility is an area of growing global attention among transportation planners and policymakers. This paper aims to portray spatiotemporal variations of car and public bus accessibility in the context of a city in a developing country: Dhaka, Bangladesh. The public bus system in Dhaka is characterized by a semi-formal arrangement which means there is a lack of available data, for example, General Transit Feed Specification, which poses great difficulties in the study of accessibility. Given these limitations, we have presented the concept of major destinations to analyze spatiotemporal accessibility based on the simple understanding that trip purposes, time of day, and trip destinations are interlinked in an urban area, and different locations would attract a different number of trips based on the time of day. Using a spatial autocorrelation approach, we identified the statistically significant destination clusters in Dhaka by peak and off-peak hours. We measured accessibility to the major destinations using a cumulative opportunity-based metric followed by estimation of the Modal Accessibility Gap (MAG). The findings indicated that, regardless of the trip origins and time of day, dependence on public transport puts the users in a substantially disadvantageous position. From the policy perspective, we have suggested the introduction of a formal public transport system in Dhaka, particularly targeting the traffic analysis zones with higher MAG. Such an approach would lead to better resource usage while providing enhanced public transport services for both peak and off-peak hours and limiting dependence on cars.