A creditor can look to execute on, or force the sale of, a debtor's assets. If the debtor jointly owns an asset, like a vehicle, it may be possible to force the sale and take part of the proceeds (the part belonging to the in-debt owner). However, if your car is financed and the loan is not paid off--at least if there's still a fair amount owing--it is unlikely this will happen, since the company that financed the car will have to be paid first from the proceeds of a sale, potentially leaving very little. That said, this is something that could potentially happen. The fact that your mother didn't pay for the car doesn't matter in this context, not if she is a co-owner; it's possible that you might in turn have a claim against your mother, but that doesn't affect a creditor's claims on her assets or share of assets.