First off, you did a mistake. You "got to know the product you are selling" so you can tell those with the "this seems broken or that don't work" to "Eff Off." They obviously are not a serious buyer...as they do not have the money.
With any used car there is certain characteristics that is that car. It is underpowered ...right from the factory... Either like it or leave it. VW slug bugs were ugly right from the factory and underpowered and they outsold the FORD MODEL T. People bought them and almost paid the new price for an old car when it was being sold 5 years later. It never seemed to lose it value. It was high in demand even though it was the pits to warm up inside when there was snow on the ground and there was no A/C, auto transmission, power brakes or other stuff. That is the car that was produced. Not a defect. Just that car brand.
. Then you know exactly what you are selling so anything they say is B.S. Wait for the next buyer...as there is always more than one person looking for the same vehicle.
Or you can do what you did...Give the car away for less money than you wanted just to get rid of it. No car lot dealer EVER WOULD DO THAT. They know there are so many "suckers out there" another will bite at the hook if they wait longer. Maybe wait an hour, day or week and they sell it for what they asked.
After the car is sold your business with this person is OVER. You don't know him or the car he is talking about.
That is you should have got full payment IN CASH. Then he is a stranger to you. All car dealers are like that.
I would not worry about it. The feedback thing is not important. Most people who shop do not pay it any attention because there are always unsatisfied buyers,,,,there is no way they can use this for leverage against you as you sold your car. It is not your living.
What you can do is.....now that you mention it is a "he" ...report that you have seen a car fitting the description with a general description of the person LURKING AROUND PLAYGROUNDS where young children play and he is offering them rides....your name is Jack Daniels. Just doing the community watchdog thing.
Or he is dealing in drugs from his vehicle. ......your name is Jack Shelak you are watching out for nefarious activities in your community. For the safety of the Kids.
All of a sudden he does not have time to bother you anymore. And you got him good as he riled you up.
He is messing with the wrong person.
All of a sudden, my answering machine speaks Polish.