bash-3.2$ mech-dump --forms "http://www.carzone.ie/usedcars/"
GET http://www.carzone.ie/usedcars/index.cfm [form1]
  fuseaction=search              (hidden readonly)
  MakeID=                        (option disabled) [*/Any Make]
  xMakeID=                       (hidden readonly)

##</code><code>##

use strict; 
use warnings;

use WWW::Mechanize;
use HTML::Form::ForceValue;

my $m = WWW::Mechanize->new( autocheck => 1 );
$m->agent_alias( 'Windows IE 6' ); 

$m->get("http://www.carzone.ie/");
$m->follow_link( url_regex => qr/Used/i );

$m->set_fields(
    #MakeID             => '32',
    #ModelID            => '281',
    #CountyID           => '10',
    xMakeID            => '32',
);

$m->form_name("form1")->find_input("MakeID")->force_value("32");
$m->form_name("form1")->dump;

##</code><code>##

GET http://www.carzone.ie/usedcars/index.cfm [form1]
  fuseaction=search              (hidden readonly)
  MakeID=32                      (option disabled) [:/Any Make|*32]
  xMakeID=32                     (hidden readonly)