Legal Question in Legal Ethics in Wisconsin

You may have a claim against him for unjust enrichment to the extent that you have paid for the car (or will become liable for paying it in the future if he defaults). However, your situation is not one which I would ever recommend, particularly due to the damage which will be done to your credit if he does not pay for the car. I see this scenario very frequently in my law practice and I usually end up filing a bankruptcy for the person who was doing the "favor" after the car has been repossessed, leaving a huge leftover balance due ("deficiency judgment"). Suing the real owner of the car if often not even worth the expense because a person with such bad credit that they cannot get their own car loan often is not able to improve his or her financial situation later; they started the "relationship" broke and remain that way after they default. Suing them therefore ends being rather meaningless. My comments here are not intended as legal advice; you really need to retain your own attorney and revisit this issue.