The following is a draft translation from Arabic.
Question: Is a woman allowed to ride a private car alone -without a Mahram (unmarriageable person), if the driver was an acquaintance of her family?
1. What applies on the home applies on the private car, because both need a permission to enter (ride).
2. Therefore no one is allowed to be in it with the woman, other than her Mahram or husband, similar to the home.
3. Nothing is excluded from that, except what the text had excluded in the homes, such as the relation of kinship for the relatives, whether they were Mahram such as the uncle or not Mahram without Khulwah (private) such as the cousin, it is allowed to visit their kinship in feasts for example and so on, because general texts were mentioned in the kinship relation: necessity of the bond for the kinships, recommend relationship for the kinships who are not Maharem without Khulwah (private).
And any other case, if it has a text which allows Ijtima’ (the meeting) of men and women at home.
4. Another exception was mentioned in the private means of transportation (which is similar to the home, because it needs permission) which is to allow a woman to ride with her driver if he has a kinship with her, but not in Khulwah (seclusion), meaning there should be others in the car from her acquaintance or those of the driver, whether they were Mahram for her or not.
The proof on this exception is the Hadith narrated by Asma -may Allah be content with her- and reported by Al-Buhkari from Asma Bint Abi Bakr -may Allah be content with them- she said:
«تَزَوَّجَنِي الزُّبَيْرُ ... وَكُنْتُ أَنْقُلُ النَّوَى مِنْ أَرْضِ الزُّبَيْرِ الَّتِي أَقْطَعَهُ رَسُولُ اللَّهِ -صلى الله عليه وسلم- عَلَى رَأْسِي وَهِيَ مِنِّي عَلَى ثُلُثَيْ فَرْسَخٍ فَجِئْتُ يَوْمًا وَالنَّوَى عَلَى رَأْسِي فَلَقِيتُ رَسُولَ اللَّهِ -صلى الله عليه وسلم- وَمَعَهُ نَفَرٌ مِنْ الْأَنْصَارِ فَدَعَانِي ثُمَّ قَالَ إِخْ إِخْ لِيَحْمِلَنِي خَلْفَهُ فَاسْتَحْيَيْتُ أَنْ أَسِيرَ مَعَ الرِّجَالِ وَذَكَرْتُ الزُّبَيْرَ وَغَيْرَتَهُ وَكَانَ أَغْيَرَ النَّاسِ فَعَرَفَ رَسُولُ اللَّهِ -صلى الله عليه وسلم- أَنِّي قَدْ اسْتَحْيَيْتُ فَمَضَى ...»
“I got married to Al-Zubair…. And I used to carry seeds on my head from the land of Al-Zubair which Rasulallah (saw) gave to him, the land is about one third of a Farsakh (parasang) away, one day while carrying the seeds on my head, I met Rasulallah (saw) with some men of the Ansar, he called me and asked me to ride behind him, I was shy to walk with the men and remembered Al-Zubair, who was a very jealous man, so Rasulallah knew that I was shy so he went along….” (the Farsakh (parasang) is about three miles, about 5.5 kilometers).
We understand from this Hadith that:
Rasulallah (saw) allowed Asma to ride behind him on his horse which is a private one and not for public transport.
Rasulallah (saw) was going with a number of his Sahabah -may Allah be content with them- in a caravan, going on together.
It is obvious that the traveling was a short one and not a long one to necessitate a Mahram.
That Rasulallah stopped to let her ride, because she is related to him in kinship, because she is the sister of Aisha –Um-ul Mu’mineen- wife of Rasulallah (saw).
We understand from the stopping of Rasulallah (saw) for her, that he knows her well because she is related to him in kinship, and she is a woman whose family has friendship with the owner of the horse or the private car, relying on the Ayat which included the friend with the kinships in the issue of eating from houses (private life) Allah (swt) said:
((...أَنْ تَأْكُلُوا مِنْ بُيُوتِكُمْ أَوْ بُيُوتِ ءَابَائِكُمْ أَوْ بُيُوتِ أُمَّهَاتِكُمْ أَوْ بُيُوتِ إِخْوَانِكُمْ أَوْ بُيُوتِ أَخَوَاتِكُمْ أَوْ بُيُوتِ أَعْمَامِكُمْ أَوْ بُيُوتِ عَمَّاتِكُمْ أَوْ بُيُوتِ أَخْوَالِكُمْ أَوْ بُيُوتِ خَالاَتِكُمْ أَوْ مَا مَلَكْتُمْ مَفَاتِحَهُ أَوْ صَدِيقِكُمْ))
“…that ye should eat in your own houses, or those of your fathers, or your mothers, or your brothers, or your sisters, or your father's brothers or your father's sisters, or your mother's brothers, or your mother's sisters, or in houses of which the keys are in your possession, or in the house of a sincere friend of yours.” [Al-Nur: 61]. The friend is the one in whom friendship is realized, meaning intimacy and affection.
The Conclusion: A woman is allowed to ride in a private car if she has kinship with the driver or her family are in true friendship with the driver, but there should not be Khulwah (seclusion), meaning that the driver must have others with him (from her or his relations) who are trustworthy, because those who were with Rasulallah (saw) were from his Sahabah taking into consideration that if the driver had only one of his or her relations in the car, then he should be a Mahram for her, or else there should be more than one of her or his trusted relations, that is gathering the evidences: Rasulallah (saw) in the hadith of Asma had a number of the Ansar -more than one- but there was no Mahram in them to Asma, but in the hadith of Rasulallah to cut Khulwah by one, he conditioned that this one should be a Mahram, where he says:
«لا يخلون رجل بامرأة إلا ومعها ذو محرم»
“A man is not allowed to sit in Khulwah with a woman, without a Mahram” reported by Muslim.
So, if a man sits with a woman in a private car, she should be a kinship to him or he should be a friend of her family, but to cut the Khulwah, there should be more than one of the driver’s trusted relations or her trusted relations in the car, or one Mahram for her. And it should be a short traveling and not a long one to necessitate a Mahram.
This is in the case were men are together with (the driver and the woman) in the car. So it must like above.
But if there are women together with the (driver and the woman) in the car, (i.e. if there are women with them) then cutting khalwa in this case is discussed by (fuqaha) before, some say that if there is with the driver his wife or woman Mahram to him, then no khalwa considered, some say even if there is another trusted woman with them, then there is no khalwa ... so this case (cutting khalwa by women) can be revised in the books of the fuqaha.
By Sheikh Ata ibn Khaleel Abu al-Rashta