When you use a Credit Union to finance a car purchase, the Credit Union will often put a clause in the security agreement that allows it to secure any other debt that you may already have with that institution. Very few customers know that such a clause is in the contract when they sign off on their financing agreement.
Once the contract is in place, if the customer ever returns to the Credit Union to get a line of credit, a credit card or any other kind of loan that would normally be completely unsecured, the car will automatically serve as collateral for the new would be unsecured loan. These cross-collateralized loans are a real hazard for the unwary in bankruptcy.