The agreement, announced on Wednesday, cements Marchionne's reputation as the industry's consummate dealmaker about a decade after he took the helm of Fiat as a car business newcomer, analysts and bankers said.

But it remains to be seen whether a merger will be enough to cut Fiat's losses in Europe. Marchionne's plan to shore up Fiat depends on the ability to share technology, cash and dealer networks with Chrysler, the No. 3 U.S. automaker.

"This is an increasingly American company now, because in Europe, and especially in Italy, the business conditions remain difficult," said Andrea Giuricin, transport analyst at Milan's Bicocca University.