a car driven by someone who is not her maḥram, even though that is a forbidden form of seclusion.

Shaykh Muḥammad b. Ibrāhīm Āl al-Shaykh, former Grand Mufti of Saudi Arabia, says in his Majmūʿ al-Fatāwā (10/52): “Today there is no doubt whatsoever that a non-maḥram woman riding alone with the owner of a car without a maḥram accompanying her is an obvious evil. It entails a number of serious harms that must not be taken lightly, whether the woman is retiring and reserved (1) or accustomed to appearing in public (2). Any man who is content for his female relatives to do this is weak in faith, deficient in manliness, and lacking proper protective jealousy over his dependants. The Prophet ﷺ said, ‘No man ever sits in seclusion with a woman but that Satan is the third of them.’ Her riding with him in a car is even more serious than being alone with him in a house or the like, for he can take her wherever he wishes—inside or outside the city—willingly or unwillingly, and the resulting sins are more grave than those that stem from simple seclusion.” End quote.

Moreover, the person whose presence lifts the prohibition of seclusion must be an adult; the presence of a small child is not enough. Some women imagine that if they take a child along the seclusion is nullified, but this notion is mistaken.

Imām al-Nawawī said (9/159): “If an unrelated man is alone with an unrelated woman…"