Is it permissible to benefit from insurance to pay for car damages, or must the full value of the car be paid to the rental office?

If the insurance is cooperative (تكافلي) and the conditions for compensation eligibility apply to what happened to the car, then there is no harm in that. However, if the incident is not covered by the insurance, or if it was the result of recklessness from another person to whom you gave the car, then it is not permissible to defraud the insurance company by concealing the truth, and you bear the consequence of your negligence.

If the insurance is commercial, based on Gharar (excessive uncertainty) and gambling, then it is forbidden, and it is not permissible to participate in it voluntarily. In such a case, the participant is only entitled to benefit from what they themselves contributed.