private void saveBtnClicked(object sender, RoutedEventArgs e)
 {
     if (!ValidateFields())
     {
         return;
     }
     Model.Car tempCar = staffMenu.ObservableCar[carList.SelectedIndex];
     MyController.manageCars.SaveCar(tempCar, tempCar.CarId);
     staffMenu.updateCarList();
 }