Comfort and Convenience
Cabin temperature is the preference people disagree about most. A comfortable setting depends on clothing, on where someone sits relative to the sun, and on simple personal tolerance, so an agreement reached at the start rarely lasts the whole journey.
Safety and Driver Assistance
A few minutes before setting off is the right time to locate the lights, wipers and hazard switch. Doing it while parked means nothing has to be searched for later, with passengers talking and the road demanding attention.
Multimedia and Connectivity
Phone battery is the common worry on a long trip, since navigation drains it fastest. If power outlets are available, agreeing who uses them avoids a small disagreement later; music and calls are separate questions, settled separately.