GM, Ford Raise U.S. Sales Incentives  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; and Ford  Motor Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=F.N target=/stocks/quickinfo/fullquote"&gt;F.N&lt;/A&gt; launched new U.S. sales incentives on Friday as  both automakers struggle with falling market share and high  inventories of unsold vehicles.