I have noticed that alot of players who try to sell cars have no other chance to advertise/sell their cars using mainchat (which is illegal) or in game adverts. So I think creating a forum section in which people can sell their cars with information about vehicle and images would be a good idea. People who want to buy cars would directly go there and there'd be a healthier environment. Plus there will be no fees for the usage of this section.
If this suggestion gets accepted I volunteer to take the responsibility of managing this newly created forum section.