[Threshold]

Try this:

pawn Код:

if(strcmp(cmd, "/respawnallcars", true) == 0 || strcmp(cmd, "/rac", true) == 0) //
    {
        if(IsPlayerConnected(playerid))
        {
            if(PlayerInfo[playerid][pAdmin] < 1337) return SendClientMessage(playerid, COLOR_GRAD1, "   you are not authorized to use that command!");
            new bool:unwanted[CAR_AMOUNT];
            for(new player=0; player<MAX_PLAYERS; player++)
            {
                if(IsPlayerInAnyVehicle(player))
                {
                    unwanted[GetPlayerVehicleID(player)]=true;
                }
            }
            for(new car = 1; car <= 359; car++)
            {
                if(IsATLCar(car) || IsATrailer(car)) continue;
                if(!unwanted[car]) SetVehicleToRespawn(car);
            }
            GetPlayerName(playerid, sendername, sizeof(sendername));
            format(string, sizeof(string), " Toate vehicule sau respawnat de %s.", sendername);
            BroadCast(COLOR_WHITE,string);
        }
        return 1;
    }

You are searching for the vehicle id of the player who used the command /rac rather than all connected players...