Yichud Car

Igros Moshe (EH IV #65.3) Question Is it permitted to travel alone with a woman in a car ? Answer As a first choice is definitely not permitted. This is even if the majority of the trip is on a major highway that even at night there are always many people in cars. That is because it is always possible to leave the highway to a quiet side street. Even travel during the day is problematic since he can easily go to a secluded area and be intimate and this is clearly a concern at night where intimacy can easily occur in the car itself. Nevertheless in time of great need such as a woman of his neighborhood requests a ride or needs to get to his destination  and if he refuses to give her a ride he is viewed as a selfish or cruel person. If a non Jewish women makes the request and he refuses than he might cause hatred to Jews. Therefore there is a basis to permit it because there is no halachic requirement to be concerned that he might go to a secluded place with a normal religious person but only that he might be overwhelmed with lust. While this seems to be a halachic dispute, one can rely on the lenient view in time of need.