When is the supplication for riding a car recited: while it is stationary before driving it, or while it is in motion? And when is the supplication for leaving the house recited: when the car starts moving, or before it starts moving? And should the supplication be recited in a low voice, a clear voice, or silently to oneself?

The supplication for riding a car and similar vehicles is recited upon settling in it, as narrated in the hadith of Ibn Umar, may Allah be pleased with them both, that the Prophet, peace and blessings be upon him, when he settled on his camel, would say "Allahu Akbar" three times. As for the supplication for leaving the house, it is recited upon exiting it, as narrated in the hadith of Umm Salamah, may Allah be pleased with her, that when the Prophet, peace and blessings be upon him, left his house, he would say: "Bismillahi, tawakkaltu 'ala Allah (In the name of Allah, I have relied upon Allah)." Both of these supplications should be recited audibly without exaggeration, such that someone nearby can hear them but not someone far away.