Connected cars are capable of communicating with other devices (e.g., other vehicles, smartphones, road side units) in their environment. The domain in which they operate is a highly dynamic one. Reasons for this include changing demands of users and heterogeneity of technologies and interfaces. Due to this, developing a concept for a digital twin of a connected car that is capable of operating under these conditions is a challenging task. Especially handling of data and behavior of connected cars is an area of interest. In this thesis, we propose a digital twin architecture which can be used to implement connected car scenarios. We analyze challenges of the domain and assess in which ways and under what circumstances connected cars may interact. Based on these expectations, we introduce our concept for a digital twin. Our main goal is to provide interoperability between different car manufacturers, while still allowing developers to implement functionality in a way they deem appropriate. In order to verify our concept, a prototype of a digital twin is implemented. We explain this implementation and share experiences gained during this development. Finally, we draw conclusions on the concept as a whole and how it may be used in practice.