Technically, the amount of the forgiven debt can be reported as income. I'm not sure how they would calculate it on a car loan. Generally, Social Security benefits are exempt from execution, levy, attachment, garnishment, or other legal process, or from the operation of any bankruptcy or insolvency
law. The exceptions are that benefits are subject: (1) to the authority of the Secretary of the Treasury to make levies for the collection of delinquent Federal taxes and under certain circumstances delinquent child support payments; and (2) to garnishment or similar legal process brought by an individual to enforce a child support or alimony
The IRS can take 15% of your social security retirement benefits under the automated Federal Payment Levy Program (FPLP); however there is no such restriction on the non-FPLP (manual) levies. An exemption
amount for reasonable living expenses may be requested, or be applied, to any levies.
So the short answer is yes, the IRS can reach a portion of your social security but you would get advance notice a long time before it came to that (if at all) and an opportunity to make other arrangements.
I do not think you need to worry about it at this point.