Shares of Detroit's Big Three automakers edged higher Tuesday as the companies spared little fanfare in showcasing their latest models at the annual North American International Auto Show in Motown. General Motors ( GM), Ford ( F) and DaimlerChrysler ( DCX), along with a slew of other automakers, were exhibiting their vehicles of the future in an effort to convince the crowds on hand that they're ready to compete for precious sales in an increasingly crowded market. The new year promises to be a crucial test for Detroit as the Big Three face slowing sales and unrelenting competition from foreign-based competitors like Toyota ( TM) and Honda ( HMC). In an effort to hold on to customers and pay their burgeoning legacy costs, the Big Three have kept production high in recent years and used aggressive price cuts and cheap financing to move vehicles off dealer lots. Profitability suffered as a result, and GM Vice Chairman Robert Lutz signaled to reporters on Tuesday that that is not sustainable. "We are no longer doing the things that used to get us two to three extra points of market share," Lutz said, according to The Wall Street Journal. "We've got to discipline ourselves." Sacrificing market share in order to boost profits is a strategy that will please Wall Street, but accepting lower revenue and market share levels also means slashing more jobs and shuttering more factories. With U.S. automakers facing important negotiations with the United Auto Workers union on a new labor contract this year, such strains could spell trouble for the industry on its already shaky labor front.