Unlikely this is an "oral contract." Most car loans are written. If you paid something in 2017, then it will still be within limitations until 2021. They can sue you. They can repossess the car. They can do both.
As mentioned, chargeoff means NOTHING to you (either as far as collections go or tax liability). It means the lender has declared it UNLIKELY that they will recover the amount. It's an accounting issue for him alone. It doesn't mean he (or his assignees) can't still try to collect. It certainly is NOT loan forgiveness.