Today CFO Journal launches a new weekly column guest written by a CFO. Dan Ammann, CFO of General Motors, kicks it off with firsthand insights into the challenges facing finance departments and the evolving role of finance chiefs. “The automotive business by its nature has a low margin for error,” Mr. Ammann writes. It is highly competitive, capital-intensive, cyclical, global and technology-focused, and it has long product cycles and vast supply chains and distribution networks. So finance can’t just be a scorekeeper—it has to be a driver of, and partner to, the business.