A processor-implemented system for automatically controlling the functionality of a mobile device of a driver while driving so as to reduce driving distractions related to the mobile device. The system detects driving and automatically enters a driving mode when driving is detected. The driving mode implements an alternate user interface (UI) that limits interactions with the mobile device in accord with predetermined restrictions. The driving mode can be configured to automatically screen incoming calls and texts while suppressing potentially-distracting notifications. The system implements a PIN-based mechanism that ensures user compliance while enabling an opt-out feature usable under controlled circumstances.