I suggest writing back to the person that signed the letter and say that the loan was discharged in bankruptcy and attach a copy of your discharge papers. You might also remind them that they are violating the US Bankruptcy Code by attempting to collect a debt that's been discharged in bankruptcy.

At the same time call the trustee and find out if he wants the car. That your lawyer told you it would belong to the court was just general information (which you might just have misunderstood) and does not obligate the court to take it. That means you have to get the yes or no directly from the trustee, preferably on a written document claiming the car for the trustee or waiving it.