[Threshold]

https://sampwiki.blast.hk/wiki/OnUnoccupiedVehicleUpdate

Quote:

Returning 0 in this callback will stop the vehicle's position being synced to other players. Update is still sent to the updating player. Useful for combating vehicle teleport hacks.

Another thing you should consider is monitoring whether the player has changed vehicles within a certain time limit. Hacks like this either rely on unoccupied vehicle updating or physically entering multiple vehicles and teleporting them. So you can monitor if their vehicle ID has changed within a reasonable time and then issue the appropriate consequences.