The mobile car parking (MCP) app provides users to locate a car park and park his/her car, which is expected to contribute to sustainable transportation. Previous mobile phone-based studies have also advocated that mobile apps create a social network among the users. However, MCP studies have yet not addressed the notion of such social capital which is expected to contribute to the sustainable transportation in a city. MCP, in fact, can also create a communication network among car owners, drivers, and car park owners and offer a unique base for studying social capital and resource utilization opportunities. To reduce the gap in existing studies, in this study, an android-based MCP app was developed as a tool to study the components of social capital. After developing the MCP app, two focus group studies were conducted to explore the components an MCP app can provide. Lastly, we linked the social capital components to the sustainable transportation goals. This research pinpointed several social capital components that are addressable to sustainable transportation, including information exchange, communication, connectedness, time-saving capabilities, mobility, coordination, plan-based journeys, and an opportunity to generate income from the social network. Moreover, very few studies have reported that social capital empirically contributes to time-saving capabilities, mobility, sustainable transportation through improved coordination in car parking management, and improved journey based on car parking decisions which are new contributions to social capital. This research is significant, as most of the mobile-based social capital research concentrated on bonding, bridging, and networking among social network members. However, this research has expanded the components of social capital in many directions. Furthermore, from the research methodological perspective, this research adopts a new approach through a combination of experimental research and focus group study.