Ferrari's new matte-liveried car for 2019 looks "extremely fast".

That was not just the observation of Renault driver Nico Hulkenberg, but almost everyone else as winter testing kicked off in Barcelona.

"It looks like Sebastian (Vettel) had a good winter," smiled Christian Horner, boss of the Red Bull team.

One journalist even asked Mercedes boss Toto Wolff if Ferrari already looks the big favourite to win the 2019 title.

"How many winter tests have you done?" Wolff hit back, noting how early it is in the season.

But even the Austrian admits he was impressed by Vettel's laptime.

"I saw the time and it's quick. Ferrari is as strong as a bear," said Wolff.

Even Vettel could not contain his happiness, observing that his first real day in the red car "could not have gone better".

But when asked about the title, the German said: "We have one day of testing behind us. But we get closer to our goal each year.

"This year, we want to win a lot of races and then we should be in a position to have a say in the title.

"If I have as much fun as I did today, then I will be very happy," Vettel added.

"It was the best start to a season that I have ever had in formula one," the four-time world champion admitted. "It doesn't mean anything, but it's still nice."

However, most believe Mercedes was not trying to equal Ferrari's laptimes on Monday.

Wolff said when asked about reigning champion Lewis Hamilton: "Have you seen him?

"The weight rules have changed and he has literally come back stronger."