How to parse a web site that uses `__dopostback` ajax call with curl and php

Question

Before someone says something or "jump," I would like to say that I have read:

• Any idea on how to scrape pages which are behind __doPostBack('...');?
• DotNetNuke, PHP, Simulating a remote postback using curl
• Scraping HTML with JavaScript postbacks
• cURL post data to asp.net page
• http://techclimber.blogspot.com.es/2009/03/php-curl-and-aspnet.html

This is my function:

  function UolgetHtmlfromAjaxCallback($a_Params,$url) {

  $EVENTTARGET = $this->UolgetAtributoEventTarget($a_Params['s_EventTarget']);
  $s_smMaster = 'ctl00$cphSite$upModelo|'.$entries['target'];
  $VIEWSTATE = urlencode($a_Params['s_ViewState']);

  $options = array(
    CURLOPT_RETURNTRANSFER => true, // return web page
    CURLOPT_HEADER => false, // don't return headers
    CURLOPT_FOLLOWLOCATION => true, // follow redirects
    CURLOPT_ENCODING => "", // handle all encodings
    CURLOPT_USERAGENT => "spider", // who am i
    CURLOPT_AUTOREFERER => true, // set referer on redirect
    CURLOPT_CONNECTTIMEOUT => 120, // timeout on connect
    CURLOPT_TIMEOUT => 120, // timeout on response
    CURLOPT_MAXREDIRS => 10, // stop after 10 redirects
    CURLOPT_POST => true,
    CURLOPT_POSTFIELDS => 'ct100%24smMaster='.urldecode($s_smMaster).
                          '&__EVENTTARGET='.urlencode($EVENTTARGET['target']).
                          '&__EVENTARGUMENT='.urlencode('').
                          '&__EVENTVALIDATION='.urlencode($s_Eventvalidation).
                          '&__VIEWSTATE='.$VIEWSTATE.
                          '&ct100%24txtBuscaNome='.$a_Params['ctl00_txtBuscaNome'].
                          '&__ASYNCPOST=true'
                          );

  $ch = curl_init( $url );
  curl_setopt_array( $ch, $options );
  $result = curl_exec ($ch);

  return $result;
  }

The $VIEWSTATE is okay, and the $EVENTTARGET is an array with these values:

Array ( 
 [id] =>          ctl00_cphSite_fichaTecnicaEditorial_rptCarrosFichaTecnica_ctl00_lbtnFichaTecnica 
 [target] => ctl00$cphSite$fichaTecnicaEditorial$rptCarrosFichaTecnica$ctl00$lbtnFichaTecnica ) 

I'm trying to use this code to scrape this website:

http://comparecar.uol.com.br/Modelo/Volvo-Xc60

And I get the website, but not the car's information.

I edit my own information.

I'm working with Tamper Data and I found that the post uses different parameters:

• ctl00%24smMaster
• __EVENTTARGET
• __EVENTARGUMENT
• __VIEWSTATE
• __EVENTVALIDATION
• ctl00%24txtBuscaNome
• __ASYNCPOST

And closes with an "="