He doesn’t want to give too much away, but Formula One star Daniel Ricciardo reckons his new car is an improvement on last year’s three-time race winner.

The Australian was encouraged after day one of pre-season testing at Jerez in Spain on Sunday, despite mechanical issues restricting him to just 35 laps.

He was fourth fastest behind former Red Bull teammate Sebastian Vettel, who put Ferrari top of the timesheets after 60 laps.

Sauber’s Marcus Ericsson (73 laps) was second quickest, ahead of Nico Rosberg of Mercedes (157 laps).

“I think, in general, everything is behaving as it should,” said Ricciardo.

“Obviously we had some issues here and there, but once the car’s running it seems pretty normal. So a good day one and obviously keep improving from here.”

The Renault-powered RB11 – in black and white camouflage livery – managed more mileage in one day than across all of last year’s pre-season testing, and that had Ricciardo upbeat.

“I can’t give too much away but we understand what we’re running here and I think it’s good,” he said.

“We still need to refine a few things with drive-ability – normal things for the start of the year – but generally I think its what we expected.

“It’s still too early to say (if it’s a step forward) but I think it is.

“We’ll see in Melbourne when everyone’s even, but for now after the first day I think there’s some positive signs.”

Ricciardo said it was no surprise 2014 champions Mercedes were among the fastest out of the garage and managed more than double the number of laps than any other team.

“They obviously came out with a pretty awesome package last year and they’re probably just refining and perfecting that even more this year,” he added.

“I expect them again to be the ones to beat coming into Melbourne.

“But I’m not intimidated either. I think it’s a reachable target for us.”

Ricciardo will return to the wheel on Tuesday, while his new teammate Daniil Kvyat takes over driving duties on Monday and Wednesday.

The season begins with the Australian Grand Prix on March 15 at Melbourne’s Albert Park.