Abandoned Vehicle - ?

Last September I traded in an old junker of a car for a brand new van at a regionally reputable/huge car dealership. Well, today I got notice that that vehicle is somehow still attached to me and that it has been impounded for abandonment. I called the lot to get it straightened out.. that's not the problem.. I'm just wondering why the dealership would have abandoned it? I know it is not sellable in my state (being military, my car was driveable etc in my home state, so i could keep it here), so it does not make sense that they would have just abandoned it because they would eventually have to get it out of the impound right? It was also abandoned in a different county than the dealership is in. The car was literally worth nothing except parts, and can't be sold in this state. It just seems shady. I am wondering if anyone has ideas about what could have happened to the car after I traded it.