Due to a major and severe exploit found within our vehicle selling script, we have had to disable it completely until we have found a viable fix. We apologise you cannot sell your vehicles to each other at the moment, however, if you want to sell your vehicle during this time, please make a ticket and give us the plate of the vehicle you want to sell along with which player it's going to and the amount, and we can manually change the owners of the vehicle for you.
We are currently investigating this issue and we will issue an update as soon as possible.