'Too early' to say title already gone - Vettel

May 11 (GMM) Sebastian Vettel insists the race for the 2016 world championship is still wide open.

After Nico Rosberg's four consecutive wins so far, some insiders are saying the Mercedes driver now has a near-unassailable upper hand over his teammate Lewis Hamilton.

And Ferrari, on the other hand, are in 'crisis' according to some sections of the Italian media, having failed to deliver on president Sergio Marchionne's pre-season target of immediate poles and wins this season.

Indeed, Vettel is already 67 points behind Rosberg in the drivers' title chase, but the red-clad German insists he is not giving up.

"We've only had four out of 21 races," he told the latest edition of Sport Bild magazine.

"I cannot remember someone saying the championship is over after four races. Whether you're talking about me or Nico Rosberg, it is simply too early," Vettel added.

In typical Maranello style, Ferrari entered the year amid high expectations and obvious resurgence, but the actual results have been less impressive, triggering the rumours of unrest.

"We may be influenced too much by either positive or negative events," Vettel said. "It is always a good idea to keep working calmly and following the plan. And analysing exactly where you need to improve."

In that vein, former quadruple world champion Vettel said he is not disheartened by Ferrari's state of progress, having joined the team only last year.

"It is normal that it is not easy to get out of a hole that was created by years of failures," said the 28-year-old. "For that, patience is required.

"And patience is exactly what is most difficult in formula one. So it is extremely important to keep working together as a team," Vettel insisted.

It took Michael Schumacher five years to help rebuild Ferrari and win his first title in red, so has his successor and former protege Vettel also set a target?

"I don't have a number," Vettel said. "Michael didn't either. The aim is to bring Ferrari forward. Preferably, of course, sooner rather than later.

"I will therefore not write off this year. That would be the wrong approach. The certain thing is that if we do everything right, we will keep getting stronger," he added.

So with four Red Bull-powered titles already in his pocket, Vettel said he is happy where he is at present.

"This is precisely the challenge I wanted when I moved to Ferrari," he said. "To build up a new team. There was never the expectation that we would be done within a year."