If the insured person had been driving the car of another person who also possesses car insurance and an accident occurred, which insurance cover should be used for the claim?

If the car had been used for personal purposes, then the insurance policy of the car that was being driven would be treated as the primary policy, if the policy had adequate coverage to cover the damages claim. However, in case the claim exceeds the coverage of the insured car, then the insurance policy of the person driving the car would be considered as secondary policy and the excess amount could be claimed from that coverage. As such, when the insurance policy of the car was inadequate to cover the damages claim, the policy of the driving person could be invoked for settlement of the claim. Still, the degree of coverage would depend on several factors like the specific reason for driving the car of another person, the state and local regulations, etc. Normally, majority of the car insurance policies would cover any driver unless that person had been specifically excluded or he/she had stolen the car. If the car owner states that permission had indeed been given for driving the car, then there would be no problem in receiving the claim settlement.