Driver State Monitoring Systems (DSMS) play a crucial role in determining whether the driver is prepared to take control of the vehicle or not. In this paper we present a cost-efficient, context-aware system, based on smartphones, which supports the driver in the driving task. This is through monitoring the driver attention and drowsiness, in addition to detecting pedestrians and vehicles. The detection rates obtained 85% in the case of pedestrians and over 90% in the case of vehicles, along with the results of the driver state, measured by closed eye duration, proved the viability of the proposed approach to provide situational awareness in the novel paradigm of autonomous driving.