Filed under: Bad news, Industry, Competitive strategy, Ford Motor (F), General Motors (GM)Ford (NYSE: F) and GM (NYSE: GM) have decided to get more deeply into the incentives business. At the beginning of the year, both companies said they would try to avoid this sort of expensive marketing.Ford will extend cash give-backs on its pick-ups. Sales of it flagship F-series have been faltering and Toyota (NYSE: TM) has offered aggressive cash discounts on its new Tundra. GM was pounded by a 21% drop in its units sales in June. The company has unusually aggressive discounts that go as far as 0% financing for 60 months on some models it sells in California.The new offers go against the logic that Detroit has employed in trying to get Wall ...