Bloomberg: Rinaldo Rinolfi may have the key to making Fiat SpA’s partnership with Chrysler Group LLC work. The 62-year-old engineer, who designed the Fiat diesel engine in the 1990s that became an industry standard and powers some of Europe’s most energy-efficient cars, has a new invention he says will cut fuel consumption by at least 10 percent. His work is at the heart of the Fiat technology that Chrysler said was worth $10 billion when they formed the alliance. “We needed to do …