I work for a private company in the department which supervises the company’s projects. Our company has its own cars which are rented from one of the car rental companies for the use of our company. Please note that the value of the fee paid to the car rental company includes comprehensive insurance for the car against any accident, Allah forbid. (Although we we have some reservations about the car insurance because it is haraam according to sharee‘ah). But this is the situation with regard to the company cars. Based on that I want to ask you about the ruling on using the company car allocated to me for personal use, knowing that I will pay for gas, oil change, filters and car washes only from my own money, because these are things that are consumed when using it. Please also note that our company has no additional expenses as a result of using the company car for personal use, apart from what I have mentioned above. Even accidents are covered by the same insurance. I would also add that if the car is only used for work, there would never be any savings for our company; the rate of use would be very low and would not be worth the cost of renting that is paid for the car; rather the only one to benefit would be the car rental company. Please note that it takes the full amount for the rental period regardless of how much it is used, which is regarded as expenditure with no benefit. Based on that, we hope that you can advise us, may Allah reward you with good, about the shar‘i ruling on this matter. If the ruling is that it is permissible as long as one takes permission from our company, is it sufficient to take permission from our manager only? Please note that he is in charge of allocating cars, taking them away and everything that has to do with them. May Allah guide you to what is true and right.
It is not permissible to use equipment belonging to one's work, such as cars and the like, for personal purposes except with permission from the company owner or from one who has the authority to give permission for that.
If your direct supervisor is giving you free rein in using these cars and he has the authority to give them to the employees outside working hours, and he has given you permission to do that on condition that you bear the expenses of fuel and so on, then there is nothing wrong with it, because it is the property of the company and it has the right to dispose of it by means of rental, giving and so on.
This applies if you are working in a private company as you said. But in the case of government institutions, it is not permissible to use their equipment for personal purposes, even if the boss gives permission for that, because he does not have the authority to allow that for himself, so how can he give permission to others to use it? This has been discussed previously in the answer to question number 47067.
And Allah knows best.