  Internet of Vehicles (IoVs) consist of smart vehicles, Autonomous Vehicles
(AVs) as well as roadside units (RSUs) that communicate wirelessly to provide
enhanced transportation services such as improved traffic efficiency and
reduced traffic congestion and accidents. IoVs, however, suffer from issues of
security, privacy and trust. Blockchain technology has been emerged as a
decentralized approach for enhanced security without depending on trusted third
parties to run services. Blockchain offers the benefits of trustworthiness,
immutability, and mitigates the problem of single point of failure and other
attacks. In this work, we present the state-of-the-art of Blockchain-enabled
IoVs (BIoV) with a particular focus on their applications such as
crowdsourcing-based applications, energy trading, traffic congestion reduction,
collision and accident avoidance and infotainment and content cashing. We also
present in-depth applications federated learning (FL) applications for BIoVs.
The key challenges resulted from the integration of Blockchain with IoV is
investigated in several domains such as edge computing, ML, and FL. Lastly, a
number of open issues and challenges as well as future opportunities in the
area of AI-enabled BIoV, hardware-assisted security for BIoV and quantum
computing attacks on BIoV.
