Comfort and Convenience
Some passengers want daylight and an open view; others prefer shade and dimmer surroundings. Sensitivity to glare varies with eyesight, age and the direction travelled, so no single arrangement suits a whole car.
Safety and Driver Assistance
Warning symbols are easier to interpret when they have been read about calmly beforehand rather than met for the first time at motorway speed. Familiarity turns an unknown light into a decision.
Multimedia and Connectivity
Long drives often bring calls about arrival times. Where hands-free calling is offered, it is worth checking beforehand how a call is answered and ended, since fumbling mid-journey helps nobody.