In recent years, the combination of novel context-aware systems with the Internet of Things (IoT) has received great attention with the advances in network and context-awareness technologies. Various context-aware consumer electronics based on IoT for intelligent and personalized user-centric services have been introduced. However, although the paradigm of the IoT has evolved from smart objects into social objects, the existing context-aware systems have not reflected the changes in these paradigms well. Therefore, this paper proposes a social enabler (S-Enabler) in order to overcome this limitation. The S-Enabler plays an important role in converting the existing objects into social objects. This paper presents the middleware architecture and cooperation processes for a social IoT-based smart system. In this paper, the S-Enabler is designed to be applied to a vehicle and an energy saving service is introduced by using the S-Enabler. The proposed energy saving service can reduce energy consumption and fuel consumption based on social behaviors such as sharing or competition. The performance of the S-Enabler is discussed through a simple vehicle service scenario. The experimental results show that the S-Enabler reduced fuel consumption by up to 31.7%.