What are the limits of permissible speech between a driver and non-mahram women, and what is the ruling on speaking with a non-mahram woman if she is accompanied by a man?

A driver's speech with foreign women is permissible when there is a need, such as asking for directions or determining the fare, returning greetings, and expressing thanks, as long as there is no fitnah (temptation/strife). If the passenger is a man and he is accompanied by a woman, the need is met by the man speaking.