To achieve end-to-end delivery in intermittently connected mobile Internet of Vehicles (IoV) networks, epidemic routing is proposed for data dissemination at the price of excessive buffer occupancy due to its store-and-forward nature. Typically, epidemic routing should be controlled to reduce system resource usage (e.g., buffer occupancy) while simultaneously providing data delivery with differentiated level of statistical guarantee. With the aid of social connectivity among vehicles, the control of data dissemination could be benefited from the property of instant end-to-end communication in Social IoV (SIoV). In particular, social links are leveraged to deliver control message for balancing the tradeoffs between buffer occupancy and data delivery reliability for supporting data dissemination in SIoV. In this paper, we proposed two representative schemes: the global timeout scheme and the antipacket dissemination scheme, respectively, for lossy and lossless data delivery, where control messages are delivered in social-based end-to-end and local-based ad-hoc fashions. For lossy data delivery, our investigation shows that with the suggested global timeout value, the per-node buffer occupancy only depends on the maximum tolerable packet loss rate and pairwise meeting rate, providing principles toward mission-critical protocols. For lossless data delivery, our analytical results show that the buffer occupancy can be significantly reduced via fully antipacket dissemination, providing efficient end-to-end communication. The developed tools therefore offer new insights for epidemic routing protocol designs and performance evaluations for SIoV.