Comfort and Convenience
Comfort preferences rarely match: one person wants cooler air, another more warmth, and seating position is partly a question of height and habit. Agreeing on settings early saves repeated adjustment once a journey is underway.
Safety and Driver Assistance
Knowing where the lights, wipers, demister and hazard switch sit before setting off means they can be used without searching for them. Preparation of that kind is simply good practice, whatever equipment a car carries.
Multimedia and Connectivity
Phone battery is the usual concern on a longer trip, and a charging point, where one is available, keeps navigation running. Calls and music are separate matters, each depending on which connections a car supports.