Model class actually have to_xml() function but this xml schema not customizable and entity based. You can export your model as xml with bit of code:
This functionality is good for data exporting operations:

class TestModule(webapp.RequestHandler):
    def get(self):
        props = AuditLog().properties()
        data = "\n"
        for prop in props:
            data = data + "  <{0}>{{{{i.{0}}}}}</{0}>\n".format(prop)
        data = data + ""
        self.response.out.write(data)