Comfort and Convenience
Cabin temperature divides passengers more than almost anything else. What one person calls pleasantly warm another finds stuffy, because comfort here depends on clothing, recent activity and whether someone has just walked in from the cold.
Safety and Driver Assistance
Adjusting mirrors and the seat before setting off belongs to the same habit as knowing where the hazard switch sits. Preparation done stationary costs nothing, while the same adjustments made in motion compete with driving itself.
Multimedia and Connectivity
Calls taken on the move are the clearest case for hands-free audio, since holding a handset is not an option. Where a system supports it, pairing once beforehand avoids fiddling later; music and navigation prompts are separate matters.