Prepare carrots before payment at MB dealer?

Hello, my first car (therefore no sales experience) is a B-170 Bj 2008 almost 150,000km automatic. Inside pretty dry fabric seats, fresh paint damage and now noises from the control chain. The latter is for me now the reason to draw a final line and I would like to buy again a young used one from a MB dealer (or NL not decided yet). Ideally, my old one, if it is still rolling for so long, give there for “payment”. And of that unfortunately I have no idea at all. If the car were in better condition (control chain) I would have it cleaned up and try to sell it, because it is equipped with a steering wheel remote control for a hand control (priced 3000Euro with installation). Just as it is now however, I am already glad if the dealer takes off the handling and I have to take care of nothing. Nevertheless, it would be nice if one could also get something for it. However, if the car is directly in the press I can save any trouble, otherwise I would at least have a professional cleaning and possibly let it get rid of the paint.