[CoaPsyFactor]

look, I haven't told you, when you want to check vehicles id in OnPlayerStateChange, you need to do vehicleid = GetPlayerVehicleID(playerid)

pawn Code:

public OnPlayerStateChange(playerid, newstate, oldstate)
{
     new vehicleid;
     if(newstate == PLAYER_STATE_DRIVER){
          vehicleid = GetPlayerVehicleID(playerid);
          // and then you loop through grotti cars :D
     }