Power units are expected to be an even more significant performance differentiator under the new aero regulations introduce this year, and Horner is hopeful the French manufacturer will deliver a significant step.

"It's a brand new engine for this year, a change of philosophy," Horner said of Renault. "They've had a big winter.

"We're hoping for a step in performance, and if that's delivered then hopefully we can really be a challenger team this year, and give Mercedes and Ferrari a hard time.

"Mercedes for sure, they're the triple world champions, they're the team to beat. They set the bar pretty high. That's what we're aspiring to.

"Hopefully we can be a real challenger team. I think the driver line-up we have is fantastic, we've had great stability in the team, and we're excited about the year ahead."

Horner says that Red Bull has made good progress over the winter as it dealt with the demands of the new regulations.

"Any off season always has its moments and pressures and demands," he continued. "We're like a swan on the surface, paddling furiously underneath, but that's the same as any pre-season. But generally we're pretty much on target.

"I think RB13 is one of the prettiest cars that we've designed and made, because the geometry of the car under these new regulations, the proportions look right, it looks mean, it looks fast, it's that old adage, if it looks right, it tends to go alright. And this car for sure looks right."

Horner also admitted the team was as nervous as usual ahead of the car's first run in testing at Barcelona next week.

"It's always an anxious moment before the car runs for the first time, for it to drive out of the garage and down the pitlane," he said.

"The first thing that you want to see is that it comes back at the end of the lap! It's an exciting moment to see the car break cover.

"And of course the testing, people get sucked into who's doing what time, which fuel loads, who's doing what race runs, etc. It's all irrelevant, in reality.

"You've got to focus on your own programme, put your blinkers on, get through your programme of work, the developments that you want to look at.

"Because it's all going to change by the time you get to Melbourne anyway. It's interesting to see the buzz and tension that surrounds those tests, but we've become pretty good here over the last few winters at just focussing on ourselves and our own programme."