Fiat Chrysler Automobiles (FCA) CEO Mike Manley Massimo Pinca | Reuters

Even when you're on the fast track, things can move far more quickly than you expect — or so it turned out for Mike Manley. As head of Fiat Chrysler's Jeep and Ram brands, the 54-year-old Brit was considered the front-runner to replace CEO Sergio Marchionne when he was set to retire in mid-2019. Then came the news last July that Marchionne had passed away following what had been billed as routine surgery. Manley was hurriedly named his replacement. "It was a shock to the system," Manley said, during a media roundtable at the North American International Auto Show in Detroit this past week. "Even though there had been numerous conversations about succession, it suddenly became a reality," he soberly added during the annual auto show that doubled as his coming-out party as chief executive. "Regardless of the circumstances you're given, you have an obligation to show your leadership." The transition came at a challenging time for Manley and for Fiat Chrysler. Just the month before Marchionne's unexpected death, the automaker had presented a new five-year plan to analysts and the media during a well-attended session in Milan. Now, Manley would be the one who would have to implement that strategy. But life in the automotive industry seldom makes it easy to stick with the plan. Manley's quiet time has given him a chance to slide into that leadership role, shaking up a number of senior management posts while re-examining Fiat Chrysler's global strategy. He is just beginning to outline some of the changes he expects to make in the months ahead. Six months after assuming the helm, Manley already has had to navigate some fast-moving waters. The Trump administration has enacted tariffs on imported aluminum and steel, as well as on Chinese imports, and may yet enact new duties on car and car part imports from other parts of the world. The shift among consumers from passenger cars to light trucks has also continued to accelerate. Several competitors have announced major production and job cuts, others have formed new alliances, like the one announced this week between Ford and Volkswagen.

The 2020 Jeep Gladiator is introduced during a Jeep press conference at the Los Angeles Auto Show in Los Angeles, California, November 28, 2018. Mike Blake | Reuters

"It's been a bumpy year," said Manley, as he settled into a chair in a small conference room at the back of Fiat Chrysler's auto show display. And circumstances are forcing him to reexamine a number of elements from the plan Marchionne outlined, including the pace at which Fiat Chrysler migrates from conventional, internal combustion engines to battery-electric technology. That's particularly the case in Europe, where diesels were expected to provide the means to meet tough new emissions and fuel economy regulations. In the wake of Volkswagen's diesel emissions scandal, however, sales of those "oil burners" have been tumbling. "Now we have to revisit our mix in terms of electrification," said Manley, noting that the automaker likely will have to increase the speed at which it adopts hybrids, plug-ins, and pure battery-electric vehicles. Under Marchionne, Fiat Chrysler had been reluctant to embrace that technology. At one point, the former chief executive, only half-jokingly, had asked potential customers not to buy the then-new Fiat 500e battery-electric vehicle, revealing that the automaker lost about $10,000 on each one it sold. The situation hasn't much improved, Manley said this week, noting that Fiat Chrysler can recover only 60 percent of the added cost for electrified powertrain technology. That's only one element of last year's plan that will have to be revisited, said Manley, adding, "There'll be other changes to follow." "Our performance in China is really weak," he said. Fiat Chrysler is running into a variety of issues as demand has slowed over the past year in the world's largest automotive market. The old Chrysler Corp. was actually the first foreign automaker to enter China in 1984, but after the disastrous collapse of DaimlerChrysler in 2007, the Asia operation went to the German side of the partnership. It took until 2015 to launch a new manufacturing operation there, and production costs are still out of whack, according to Manley. Complicating matters, the division he ran made some fundamental mistakes in positioning Jeep to Chinese consumers — a problem it is now struggling to correct. The biggest mistake, he said, was positioning Jeep as a "professional" brand in the years before it had a local production plant. That worked well marketing American-made products like the big Grand Cherokee in low volume. But it has backfired now that the Guangzhou plant, operated in a joint venture with China's GAC, has opened. Mainstream customers have shown little interest in products they think are meant for Chinese elite, Manley explained. On the whole, though, Manley was cautiously upbeat in his assessment of where FCA stands a half year into his reign. If anything, it has already gone through the painful downsizing that has gripped both of its Detroit competitors. General Motors in November announced plans to close five factories, including three assembly plants, and trim about 14,000 jobs. Ford is readying big cuts for Europe and is expected to reveal plans for a North American restructuring by mid-year. Fiat Chrysler made most of its cuts around the time it filed for bankruptcy protection in 2010, "when we were in a mode of survival," Manley said. In sharp contrast, FCA is now adding jobs and will be opening at least one new plant, which reportedly centers around what could be a $1 billion renovation of a currently closed engine plant in the Detroit suburb of Warren, Michigan. It would be used to produce two new models for the rapidly growing Jeep brand, including a three-row model that brings back the old Jeep Wagoneer nameplate.

The 2019 Ram Heavy Duty pickup truck unveiled at the Detroit auto show on Monday, Jan. 14, 2019. Mack Hogan/CNBC