Is it permissible to take the difference in the car's value after its repair, and is it permissible to take the rental value for the period the car is in the workshop after an accident?

The basic principle is that the rented item is a trust (amana) that the renter is not liable for, except in cases of transgression (ta'addi) or negligence (tafrit). There are other reasons that necessitate liability, including: undertaking liability after the contract, or for the sake of public interest, such as holding artisans liable, or due to suspicion, or stipulating liability on the trustee – which is a point of disagreement among scholars.

Accordingly, car rental offices are permitted to stipulate the renter's liability for the car for several considerations, including: the corruption of trustworthiness in this era, the difficulty of proving transgression or negligence, and because public interest and the preservation of people's wealth necessitate it.

However, the renter is only liable for damages. Thus, he is liable for an equivalent of the damaged item if it has one, or its value if it does not. It is not permissible to hold him liable for the rental fee for the period the car remains in the workshop for repairs, because the rental contract is voided by the damage of the rented item.