Ferrari is working harder than ever for F1 success in 2017, according to president Sergio Marchionne.

He was speaking after being hailed on US president-elect Donald Trump's famous Twitter account, with Ferrari parent Fiat Chrysler having announced plans to invest $1 billion in Michigan and Ohio.

But Marchionne is also president of Ferrari, and he said of the F1 team: "The guys are working tirelessly.

"At Christmas they had only two days of vacation," he is quoted by Corriere dello Sport. "The car seems to be going well; the engine is running great on the bench.

"But this is not the time to fall for that, let's see what success we have when we get to the track. For now the work they are doing is enormous, on the engine, aerodynamics and the new rules," Marchionne said.

Marchionne admits he should not have targeted wins and the title last year, and also that aspects of how difficult the sport is surprised him.

"Yes, but do you know what my mistake was? I intervened in the team too late, but I did it out of respect. I had left them to work. If I had intervened earlier, in 2015, probably last year would have gone a different way. But who knows."

He also played down the notion that whether Ferrari can catch up next year depends mainly on Mercedes.

"We would be wrong to think like this," said Marchionne. "It is not their fault for doing great work. Maybe it is not nice, but it is true that they are good.

"No, it depends on us, so we have to focus on what we have to do to beat them."

Marchionne was also asked about the photo on Twitter depicting Nico Rosberg refuelling a Ferrari supercar, and said: "I know of no F1 driver that does not want to drive a Ferrari."

And as for his future as Fiat and Ferrari president, Marchionne joked: "Actually, I'm giving up everything because I want to be a journalist."

(GMM)