Mercedes has suffered a “setback” testing its new engine concept for next season with team boss Toto Wolff revealing it had expected “a little bit more” from what it initially delivered.

The Brackley-based outfit has dominated the hybrid era of Formula 1 since its inception in 2014 winning all 10 titles in the last five years, but this year rivals Ferrari surpassed its engines overall output mid-way through the season.

The team heads into 2019 chasing a record-equalling sixth consecutive constructors’ championship, only previously achieved by Ferrari at the start of this century.

Speaking recently at a conference for sponsor Hewlett Packard Enterprise, Wolff detailed the progress of the new car and the challenges it is facing under the new regulations.

“These rules have been changed, normally the downforce should be less but the rumours you hear from the paddock is that people have been able to recuperate lots of that.

“There is a tremendous development race that is happening as we speak in finding downforce, reducing drag. And of course the engine is a very important part, and adding more horsepower to the engine.

“So we are setting ourselves really ambitious targets. We have actually increased the targets six weeks ago because we heard some rumours that others were doing well, so we increased the final point for the first race where we need to be in absolute lap time. We are still on the slope.”

In response to speculation that teams are making gains on the power unit Mercedes increased its initial targets, unveiling lower performance numbers than expected on its concept, but remains “optimistic” it can be resolved.

“We’ve had some good weeks in the wind tunnel, we’ve had a little bit of a setback on the engine side where we believed the new concept would deliver a little bit more,” Wolff added.

“But these guys are very ambitious like all of us and so I’m optimistic. But you will never know. We will know when the first qualifying session gets underway in Melbourne.”