Improving the efficiency of Battery Electric Vehicles (BEVs) is crucial for enhancing their range and performance. This paper explores the use of virtual tools to integrate and optimise various systems, with a particular focus on thermal management. The study considers global legislative drive cycles and real-world scenarios, including hot and cold weather conditions, charging cycles, and towing. A virtual vehicle model is developed to include major contributors to range prediction and optimisation, such as thermal systems. Key components analysed include high voltage (HV) and low voltage (LV) consumers (compressors, pumps, fans), thermal system performance and behaviour (including cabin climate control), thermal controllers, and thermal plant models. The emergent behaviour resulting from the interaction between hardware and control systems is also examined. The methodology involves co-simulation of hardware and control models, encompassing thermal systems (coolant, refrigerant, cabin) and the vehicle propulsion domain (driveline, powertrain). This is achieved using a combination of 1D thermos-fluid simulation tools, multi-domain simulation, model-based design block diagram environments, and virtual ECU simulation platform models. The approach can run the entire vehicle operating range and capturing the main HV and LV consumers. The findings demonstrate that integrating thermal system plant and controls through virtual tools can significantly enhance BEV efficiency, providing a comprehensive framework for future developments in electric vehicle technology.