Is it permissible to go out with the wife of a husband’s friend and her husband on an outing, and to sit separately, knowing that they first pass by car? And is this considered ikhtilat (impermissible mixing)? And is it permissible for a niqabi wife to befriend a non-observant woman whom she has not yet come to know?

If a woman riding in a car with men does not lead to any شرعي (Shar'i) prohibition, such as physical contact, then there is no objection to it. As for the companionship of an unveiled woman, there is no objection to it if what she exposes is limited to her face and hands, taking into consideration the stronger opinion of the obligation to cover them due to the corruption of the times, and provided that she is chaste. If one fears her morals or if she is known for bad behavior, then one must distance oneself from her.