The automotive press has been relentlessly critical of Chrysler CEO Sergio Marchionne — savior of Chrysler and Italy’s auto industry — about Fiat’s return to the United States. The company’s initial foray, the Fiat 500, sold only about 26,000 units in its first year, far short of Marchionne’s 50,000 unit goal. Yet the carping misses the conundrum faced by companies planning market entry — for Fiat to get big in the U.S. market, it had to start tiny.