Yes, they can (and likely will). Report this to any insurance companies you have policies with and contact local counsel.
Personal injury cases only; I'm good at it; you be the Judge! All information provided is for informational and educational purposes only. No attorney client relationship has been formed or should be inferred. Please speak with a local and qualified attorney. I truly wish you and those close to you all the best. Jeff
You do not provide enough facts to evaluate. However if your son is driving a car and he drives carelessly and damages it, why would you think he is not responsible for his negligence.
You need to turn this over to your insurance.
If you feel this is the "best" answer or is "helpful," please indicate. Since I am limited to the information you provide, I cannot guarantee the accuracy of the answer. You should seek the advise of an attorney who can explore all aspects of your question. This communication does not form an attorney client relationship.
Who was at fault in causing the crash?
If your son was at fault, the rental company can pursue the claim against him. I would also suggest the "adult" is responsible as well and even if the adult says they're not paying, they may still be liable - the rental company doesn't care who pays however, it seems much more likely the adult could pay rather than your son.
If another party caused the crash, they would be responsible for damage to the rental vehicle.
As I said, the rental agency doesn't care who pays, just so long as it is paid - it will probably bring a claim against everybody and then see who will pay voluntarily, before filing a lawsuit.
Just because the rental agency says it has a claim and sends a collection letter doesn't necessarily mean your son is responsible - if he's at fault in causing the damage, he'll be responsible for it and in all likelihood, so will the adult who asked him to run the errand on his behalf.
Regardless, the crash and the claim need to be reported to your motor vehicle insurance company.
A roundup of the best tips and legal advice.