Google's own Search field:

    <input class="gsfi" id="lst-ib" maxlength="2048" name="q" 
    autocomplete="off" title="Suche" type="text" value="" aria 
    label="Suche" aria-haspopup="false" role="combobox" aria   
    autocomplete="both" dir="ltr" spellcheck="false"
    style="border: none; padding: 0px; margin: 0px; height: 
    auto; width: 100%; position: absolute; z-index: 6; left:
    0px; outline: none; background: ....

oh....

autocomplete="off" and autocomplete="both" really strange.