Comfort and Convenience
Cabin temperature is a common point of disagreement, since people differ in what feels pleasant. Agreeing on a setting early, or letting passengers say when they feel cold, keeps the subject from resurfacing repeatedly.
Safety and Driver Assistance
Knowing where the essential controls sit before setting off means lights, wipers and hazard switches can be found without searching. This is simply preparation, and it is worth doing whenever the car is unfamiliar.
Multimedia and Connectivity
Passengers often need to keep a phone charged on longer trips. Where a suitable socket or port is available, agreeing who uses it avoids the small negotiations that arise when several devices run low at once.