[Jstylezzz]

Use this "system":

This above OnGameModeInit, OUTSIDE any callback:

pawn Код:

new sirenon[MAX_VEHICLES];

This under OnGameModeInit, AFTER you created all the vehicles:

pawn Код:

for(new vehicleid=0;vehicleid<=MAX_VEHICLES;vehicleid++)
    {
    sirenon[vehicleid] = CreateDynamicObject(19419, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0);
    }

This at the bottom of your script:

pawn Код:

CMD:siren(playerid,params[])
{
    new vehicleid = GetPlayerVehicleID(playerid);
    if(!IsPlayerInAnyVehicle(playerid)) return SendClientMessage(playerid,COLOR_LIGHTBLUE,"You are not in any vehicle");
    AttachObjectToVehicle(siren[vehicleid],(GetPlayerVehicleID(playerid)), 0.0, 0.0, 1.0, 0.0, 0.0, 0.0);
    return 1;
}
CMD:nosiren(playerid,params[])
{
    new vehicleid = GetPlayerVehicleID(playerid);
    if(!IsPlayerInAnyVehicle(playerid)) return SendClientMessage(playerid,COLOR_LIGHTBLUE,"You are not in any vehicle");
    DestroyObject(siren[vehicleid]);
   
    return 1;
}

Hope this helps you