Buyers must prioritize CAN/LIN/FlexRay bus compatibility to ensure the module communicates correctly with the vehicle's ECU network. Key hardware specs include operating voltage (typically 9V-16V for passenger cars), standby current consumption (<1mA to prevent battery drain), and I/O port density for controlling functions like lighting, central locking, and wipers. Ensure the module uses automotive-grade semiconductors (AEC-Q100 qualified) to withstand extreme temperature fluctuations ranging from -40°C to +85°C or higher.