How is the Prophet's request for Asma to ride behind him on his mount, when she was not his Mahram, to be understood, and what is the refutation against those who might use this Hadith to permit a woman riding with a foreign driver?

This hadith is authentic, and Asma's statement, "He would carry me behind him," was a presumption on her part. This hadith has been used as evidence for the permissibility of a woman riding behind a man in men's convoys. However, the story cannot be used as evidence for the permissibility of a woman going out with a driver alone, due to the prohibition of unlawful seclusion (khalwa), based on the Prophet's (peace be upon him) saying: "No man is alone with a woman but Satan is the third of them," and his saying: "No man should be alone with a woman unless there is a mahram with her." It is more likely that a woman going out with a driver alone constitutes khalwa.