Comfort and Convenience
Cabin temperature is the classic example: one person feels cool while another finds the same setting warm. Preferences differ with clothing, seating position and simple habit, so agreeing on a setting is part of travelling together.
Safety and Driver Assistance
Learning where the essential controls sit before setting off, among them lights, wipers, mirrors and the hazard switch, means less searching later. A few minutes while stationary is the easiest time, particularly in a car driven rarely.
Multimedia and Connectivity
Phone battery is the usual concern on a longer trip with passengers, since navigation and screen use drain it steadily. Where a charging point is provided in the cabin, it is worth agreeing who uses it.