Updated example:

use strict;
use warnings;
use WWW::Mechanize;
use Crypt::SSLeay;

$ENV{HTTPS_PKCS12_FILE}     = 'certs/pkcs12.pkcs12';
$ENV{HTTPS_PKCS12_PASSWORD} = 'PKCS12_PASSWORD';

my $mech = WWW::Mechanize->new;
$mech->credentials('user', 'pass');
my $response = $mech->get('https://foo.com');

die $response->status_line unless $response->is_success;

printf "content-type: %s\n", $response->header('Content-Type');

my $data = $response->content;
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