Praise be to Allah.
There is no doubt that not fasting whilst travelling is allowed in sharee‘ah and is a concession granted by Allah, may He be glorified and exalted. Indeed Allah says (interpretation of the meaning): “but if any of you is ill or on a journey, the same number (should be made up) from other days” [al-Baqarah 2:184]. The Prophet (blessings and peace of Allah be upon him) both fasted and broke the fast when travelling, as did his Companions. So if a person breaks the fast, there is nothing wrong with it, and if he fasts, there is nothing wrong with it.
Breaking the fast is a concession granted by Allah, may He be glorified and exalted, to travellers whether the traveller is travelling by car or camel or ship or airplane. There is no differentiation in that. The traveller may break his fast during Ramadan, but if he fasts there is nothing wrong with it. If it is too difficult for him to fast, then it is better for him not to fast. For example, if it is hot and difficult, then it is better not to fast. Not fasting is emphasised so that one may avail oneself of a concession granted by Allah, may He be glorified and exalted. In the hadeeth it is narrated that the Prophet (blessings and peace of Allah be upon him) said: “Allah loves you to avail yourself of His concessions as He hates you to commit acts of disobedience towards Him.”
If it is very hot, then the Sunnah is to break the fast. The Prophet (blessings and peace of Allah be upon him) saw a man being shaded. He asked about that and they said: He is fasting. He (blessings and peace of Allah be upon him) said: “It is not righteousness to fast whilst travelling” -- i.e., for the one for whom it is too difficult. But for the one who is not harmed by that and it is not difficult for him, then he has a choice: if he wants to he may fast, and if he wants to he may break the fast.
But with regard to those drivers who spend their lives on the road, the correct view is that there is nothing wrong with it even if travelling is his profession. Those who are driving all the time, such as taxi drivers and so on, are like those who were always travelling by camel in the past. Such a person may break the fast even if he is always travelling, but when he comes to his home city, he should fast and refrain from eating and drinking. But whilst he is travelling and moving from one city to another, he may break the fast even if this is his profession.
Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him)