Fiat SpA's chief executive visits Berlin on Monday to try to convince Germany's political leaders to sign up to his vision for a new European car giant by letting him take over General Motors Corp's Opel unit.

Sergio Marchionne goes to Berlin with a one-month deadline in his sights, a newspaper report said, less than a week after he sealed a deal with Chrysler to form a partnership.

His plan would involve spinning off Fiat's core car business into a new company including Chrysler and GM Europe and listing it on a stock exchange.

An agreement in principle has to be struck in 30 days, he said in an interview in the Financial Times on Monday about a deal with Opel.

Fiat's shares jumped 6.5 percent in early Milan trade while the DJ Stoxx European auto sector <.SXAP> rose 1.1 percent.

Combining with Chrysler and Opel fits in with Marchionne's strategy for guiding Fiat through the auto industry's current crisis.

He has often said a carmaker had to make more than 5 million vehicles a year to be able to make a profit, and in December he said Fiat did not have the scale to survive the shake-out as a standalone company.

A Fiat statement on Sunday said Fiat, Chrysler and GM Europe would together have annual revenues of about 80 billion euros ($106.3 billion). It did not mention Opel, which makes up 80 percent of GM Europe's revenue.

Marchionne told the Financial Times that Fiat and Opel would reap synergies of 1 billion euros a year from the deal.

From an engineering and industrial point of view, this is a marriage made in heaven, he was quoted as saying.

The biggest opposition to a deal between Fiat and Opel will come from the unions in both countries. They fear the eventual cost savings to come out of a merger would lead to job cuts and plant closures.

The new company, tentatively called Fiat/Opel, would merge their small B and midsize C segment car platforms, and absorb Fiat's ultra-small A platform and Opel's upper-middle D platform, the Financial Times said.

'OPPORTUNITY FOR EUROPE'

Marchionne plans to ask the British government and administrations in other European countries where Fiat and Opel have plants, to offer the new company loan guarantees, the FT said.

He will say the deal is important for Europe, currently being battered by an economic downturn, the paper said.

This is a real opportunity to make the European Union work as a union, he was quoted as saying. If we don't do this, it's a failure of our efforts to create a single market.

The new company would see the Agnelli family's 30 percent shareholding of Fiat Auto diluted after the spin-off, with GM also a minority shareholder in Fiat/Opel, the paper said.

The merged company would also include Saab, GM's small Swedish brand which it is selling separately, the paper said.

The new company may also include GM's Latin American operations, the FT reported.

Ferrari and Maserati luxury carmakers would stay with the parent, the paper said.

The FT said Marchionne was considering stepping down next year as non-executive vice-chairman of UBS.

German Economy Minister Karl-Theodor zu Guttenberg said he did not expect a final decision on the future of Opel to come out of his meeting with Marchionne on Monday.

Today I just hope that I hear something more concrete than the rough draft that has already been presented to me, he told German radio, adding he was open to any potential investor.

(Reporting by Avril Ormsby in London and Gilles Castonguay in Milan; editing by John Stonestreet)

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