Co-operative automated driving (CAD) use cases involve group-based vehicle-to-vehicle (V2V) communications with a wide range of quality-of-service (QoS) requirements. This work introduces and exploits fifth generation mobile networks (5G) functional architecture support for vehicle-to-everything (V2X) applications to address V2V sidelink radio resource management (RRM) for CAD use cases. A QoS requirement-aware sidelink resource allocation optimization problem is formulated for multicast group V2V communications with reliability constraints and half-duplex limitation. Furthermore, the problem is analyzed for cloud-based sidelink RRM and a dynamic vehicular environment. Accounting for the challenges in acquiring channel state information (CSI), a low-complexity scheduling scheme is presented that makes use of slowly varying large-scale channel parameters (e.g. path loss). Simulation results show significant gains in terms of packet delay performance while meeting the reliability requirements on V2V links.