WP Dropdown Categories, display subcategories but not grandchildren categories?

To remove grand-children:

<?php $args = array(
    'show_option_none' => 'Make', 
    child_of => 5,
    hide_empty => '0',
    exclude => '0',
    hierarchical => 1,
    depth => 1
    ); ?>
<b>Make  </b><?php wp_dropdown_categories($args); ?>

You need to add the hierarchical and depth parameters.