Mr Manley, 54, has been given the tough job of succeeding Sergio Marchionne as chief executive of Fiat Chrysler.
The world’s seventh-largest car-maker said on Saturday that the highly regarded Mr Marchionne, 66, had been forced to step down. He is seriously ill in hospital in Zurich following complications after surgery on his shoulder.
Mr Manley, who was previously running Jeep, now assumes overall responsibility not only for that brand but a whole stable of well-known marques including Fiat, Chrysler, Dodge, Alfa Romeo, Lancia, Maserati and Ram.
It is a job that would intimidate many. Mr Marchionne, who was born in Italy but who holds joint Italian-Canadian citizenship, is one of the industry’s most revered figures after rescuing Fiat, Italy’s biggest industrial combine, from near-bankruptcy in 2003/2004.
This entailed plant closures and many thousands of job losses but, from it, Fiat emerged as a stronger business and one that, after making a loss of €8.3bn in 2003, was also profitable.
He gave the US car industry an early taste of his negotiating skills when, in 2005, he persuaded General Motors to pay the company $2bn not to exercise an option that would have seen Fiat’s US operations sold to GM.
The next to come up against these abilities was Barack Obama who, in 2009, was persuaded to allow Fiat to take over Chrysler, the third-largest US car-maker, in the wake of the financial crisis but without paying a cent for it.
The business has since been revitalised and, last year, sold two million vehicles in the US – twice the volume it did in 2009.
Mr Marchionne followed this by demerging the group’s industrial vehicles arm to form CNH Industrial, the company behind Iveco and Magirus, the bus and truck makers and New Holland and Steyr, the tractor makers.
He also went on to oversee the successful demerger, two years ago, of Ferrari. He remained chairman of both CNH Industrial and Ferrari until stepping down at the weekend.
Italy has been rocked by Mr Marchionne’s sudden departure and many have paid generous tribute to a man who restored confidence to the country’s manufacturing.
Matteo Renzi, the former centre-left prime minister of Italy, said: “He has succeeded in giving Fiat a future when that seemed impossible. He created jobs, not unemployment.”
Silvio Berlusconi, another prime minister, said Mr Marchionne was Italy’s “number one manager” and said he had come “to symbolise Italian genius to the rest of the world.”
Marco Bentivoglio, general secretary of the CISL metalworker’s union, added: “We have not seen eye-to-eye on certain things, but together we challenged little lazy Italy, which prefers to close plants rather than roll up its sleeves.”
A number of challenges face Mr Manley. The first is that, while Fiat Chrysler is now a successful and profitable company, most of its profits come from the Jeep and Ram brands that he was running.
Fiat, Dodge and Chrysler, arguably its best-known brands, are significantly less profitable. Some industry wags have even suggested the company be rechristened from Fiat Chrysler to Jeep Ram.
The company is also too dependent on the US, which accounts for an estimated three-quarters of its profits, while it lags both US rivals GM and Ford and European rivals like Volkswagen and BMW in electric and hybrid vehicles.
Mr Marchionne said last month that he planned to invest €9bn in that sector and in stepping up production of sports utility vehicles with the aim of doubling profits during the next five years.
Mr Marchionne also proposed to simplify the Fiat brand to just a handful of makes, including the 500 and the Panda, with the 500 in particular being refocused on the electric vehicles market.
Similarly, he planned that Chrysler and Dodge would be refocused on the US market, with the Jeep, Maserati and Alfa Romeo brands the group’s main global brands.
Jeep, in particular, was to spearhead the push into both SUVs and electric cars, while Alfa was set the target of selling 400,000 vehicles a year by 2022, up from 170,000 at present.
Maserati will also launch an electric version to compete with the likes of Tesla and Porsche. Growing sales in China, where Fiat Chrysler lags GM and Ford, is also seen as essential.
As if that were not enough of a challenge, Mr Manley has to do all this while grappling with the possible impact on the business of a growing trade war between the US and China in which tariffs on cars is one of the key battlefields, not to mention negotiating a tough landscape in which even the US is beginning to crack down harder on vehicle emissions and in which competition in SUVs is increasing.
Bedfordshire-born Mr Manley, who quadrupled Jeep’s sales during his first six years at the helm, had been instrumental in helping Mr Marchionne come up with his blueprint for the next five years.
With a degree in engineering from London’s South Bank University, he began his career in car leasing and has also worked extensively in sales, so has seen the industry from all angles.
Investors in Fiat Chrysler will be hoping the feats he has achieved with Jeep can be replicated right across the company.