Turin, April 16 - Last year was "the best year ever" for Fiat and Chrysler, John Elkann, chairman of the more than 100-year-old Italian automotive group, wrote to shareholders in Exor, the Agnelli family holding company which owns a controlling stake in Fiat and other investments. "Having achieved these results in such a difficult context shows how profound the transformation of Fiat-Chrysler has been," he said. Fiat acquired a controlling stake in Chrysler in 2009, following the US company's federal government-sponsored bankruptcy reorganization. In his letter to Exor shareholders, Elkann also praised Fiat and Chrysler Chief Executive Sergio Marchionne for "preserving capital" over the past few years. "Sergio Marchionne carefully conserved the (company's) capital, delaying investments in new models while everyone else said it was necessary to do the opposite," Elkann wrote. Marchionne's decision to not invest massively in new model launches - especially at Fiat - over the past few years has been criticized by many in the industry and is said to be one of the causes of the company's sliding car sales in a European market awash with new models.