Auto Stocks Surge After Weak Sales  DETROIT (Reuters) - General Motors Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GM.N target=/stocks/quickinfo/fullquote"&gt;GM.N&lt;/A&gt; on Thursday  led a late-day rally in auto stocks, one day after the world's  largest automaker posted dismal U.S. sales results for August  and cut vehicle production.