Possible Damage to a Vehicle

I rented a car 'under the table' from someone and drove it on a dirt road with potholes, following the instructions of Waze. The lessor claims that it is possible that the car was damaged, but he cannot prove it. I should note that he did not tell me not to drive on dirt roads. What should I do according to the law, and what should I do to alleviate my concerns even according to 'lifnim mishurat hadin' (beyond the letter of the law)?

Shalom!
Since it is not known that there was any damage, you are exempt. And this does not involve a matter of 'lifnim mishurat hadin' (beyond the letter of the law).