Some Car Dealer Groups Hurt by Weather  DETROIT (Reuters) - AutoNation Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AN.N target=/stocks/quickinfo/fullquote"&gt;AN.N&lt;/A&gt; and two other  car dealership companies on Thursday posted weaker quarterly  earnings, blaming the hurricanes that hit the U.S. Southeast  this summer or costly incentives used to boost sales.