This script will not work locally in IE version 7 and later, not in some others (notably at least some versions, including the latest at this typing of Chrome), and perhaps not in some versions of others as well if all of the pages aren't all in the same folder (the default setup in ajaxcars.zip places the external files in a separate folder). If that's a browser and/or folder setup you're testing in, either upload the pages to a server for live testing or test in a different browser.
If it won't work for you live and you want more help:
Please post a link to a page on your site that contains the problematic code so we can check it out.
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