Is it permissible for a man and woman to take a trip together alone in a car? For example, if a man is driving somewhere, and the woman who lives next door needs a ride to that location, may she ride with him even though there is no one else in the car, or does this violate the prohibition of Yihud (forbidden seclusion)? The Halachic authorities rule that as long as there are other people on the road, either motorists or pedestrians, who can look into the car, it is permissible for a man and woman to ride in a car alone together. This is permissible even at nighttime, since it is possible for other people to look into the car, and this helps preclude the possibility of inappropriate behavior. However, Rav Moshe Feinstein (Russia-New York, 1895-1986), in one of his responsa, wrote that while this is permissible according to strict Halacha, in the interest of Seni'ut (modesty) it should be avoided when possible. Even though there is no technical Issur (prohibition), it is best to avoid such a situation, unless this would cause tension and enmity, such as if the woman would feel slighted by the man's refusal to give her a ride, for example. This Halacha is codified in the contemporary work Minhat Ish – Hilchot Yihud (section 2, p. 54; listen to audio recording for precise citation). The author (Rav Eyal Shraga) adds that it is especially important for a man to avoid being alone in a car with a woman driving. When the man is the driver, his mind is focused on the road, but this of course is not the case when the woman drives, and thus this situation should certainly be avoided if possible. Furthermore, a man and woman should not sit next to each other in a car. Although it is permissible for a man and woman to ride alone together, as mentioned, this is when the passenger sits in the back, and not next to the driver. This is the ruling of Rav Shemuel Wosner (contemporary) in his work Shebet Halevi (vol.10, 237), where he writes that proper standards of modesty dictate that a man and woman should not sit next to each other when driving alone in a car. He cites the adage, "Harhek Min Ha'ki'ur U'min Ha'domeh Lo" – "Distance yourself from what is inappropriate and from what resembles it." Therefore, while it is permissible for a man and woman to ride together alone, the passenger should sit in the back. Summary: It is permissible for a man and woman to ride alone together in a car if they are driving in a place where there are pedestrians or other motorists in the area. This should preferably be avoided, but it is permissible, especially if refusing would cause tension and enmity. If a man and woman do ride alone together, the passenger should sit in the back, and not next to the driver.