You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="BAH|2656" />
  </query-continue>
  <query>
    <pages>
      <page pageid="830" ns="0" title="List of Superleague Grands Prix" />
      <page pageid="871" ns="0" title="Mike Schroten" />
      <page pageid="1576" ns="0" title="Andrejs Pestovs" />
      <page pageid="1796" ns="0" title="List of GPVWC circuits" />
      <page pageid="2065" ns="0" title="Streetfighter Racing Systems" />
      <page pageid="2268" ns="0" title="Storm Racing Team" />
      <page pageid="2272" ns="0" title="Terence Grech" />
      <page pageid="2282" ns="0" title="Adrian McNaughton" />
      <page pageid="2284" ns="0" title="Emanuel Gaczella" />
      <page pageid="2422" ns="0" title="List of Formula Challenge Grands Prix" />
    </pages>
  </query>
</api>