Title is a legal concept: when a lender is on title it means they own a security interest in collateral for a loan.
Possession means physically keeping, using or controlling a thing. Not a piece of paper constituting an indicia of ownership, but actual physical use and control.
The saying possession is 9/10ths etc., if it means anything in this context, alludes to the latter physical sense.
Dollars, perhaps even you can see that physical possession of a piece of paper called a title is of less legal and practical use than physical possession of the car itself. For instance, the last time I checked, I wasn't able to drive my car's pink slip to and from work.
Furthermore, as long as the debtor here has physical possession of the car, he has something he can bargain with. Once he loses it he's pretty much screwed.
I'd find a local legal clinic or a lawyer who does free consultations; the debtor needs specific advice on how to retain possession. That is, possession of the car Dollars, not the paper.