Cadillac is offering huge Escalade discounts for Navigator owners

ATasty margins and a willing audience make full-size luxury SUVs a cutthroat business. And we don't mean it in the "friendly afternoon soccer game way," either. Think Michael Douglas in "Wall Street." Cadillac is offering $5,000 to Lincoln owners willing to trade allegiances. The kicker? Trade in your 1999 or newer Lincoln Navigator for a