$rd_args = (array(
    'ignore_sticky_posts' => 1,
        'orderby' => 'meta_value',

        'order' => 'ASC',
             'meta_query' => array(
            array(
            'key' => 'brand',
            ),
            array(
            'key' => 'model',
            )
        )
    ));

    $rd_query = new WP_Query( $rd_args );

        $the_query = new WP_Query(array( 'meta_key' => 'votes_count', 'meta_value' => '1' ));

    $html_out = '';
    $html_out = '<select id="office-chooser2" >';
    $html_out .= '<option value="none">Select an Office</option>';
    $select  = '<select id="office-chooser">';
    $select .= '<option value="none">Select an Office</option>';


    while ($rd_query->have_posts()) : $rd_query->the_post();

        // add each div with excerp. It's ID is unique and correlates to value of select drop down
            $brand = (get_post_meta($post->ID, 'brand', true));
            $model = (get_post_meta($post->ID, 'model', true));
        $html_out .= '<option value="office-'.$post->ID.'" class="office-entry" id="office-'.$post->ID.'">'.$model.'</option>';
        $select   .= '<option value="office-'.$post->ID.'">'.$brand.'</option>';
    endwhile;

    // wrap up $select
    $select .= '</select>';
    $html_out .= '</select>';

    echo $select;
    echo $html_out;


    ?>

    <script type="text/javascript">
        jQuery(function($){
            $('#office-chooser').change(function(){
                var $selected_office = $(this).val();
                if(($selected_office == 'none') ){
                    $('div.office-entry').hide();
                    $('#office-chooser2').hide();
                    $('#' + $selected_office).hide();
                } else  {
                $('#' + $selected_office).show();
                                $('#office-chooser2').show();

    }
            });
        });
    </script>