Mercedes has been the benchmark power unit since the turbo hybrid rules came into force in 2014, and much of its advantage was put down to a unique split turbo-compressor idea that it has used since the beginning of the current rules cycle.

The idea of splitting the turbo and compressor to place them at either side of the main engine block is one that was copied by Honda for this year, after it abandoned its original idea of having the items within the V-block to help with McLaren's 'size-zero' ambitions.

Renault revamped its power unit for this year but decided against following the Mercedes design, instead keeping its turbo components at the rear of the engine.

And, having analysed carefully its progress, and the potential of its new power unit, Renault is convinced its design is good enough to deliver the performance it needs in the future.

"Are we going to split the turbo/compressor next year? No," Renault F1 engine chief Remi Taffin told Motorsport.com. "Our engine is as it is. We decided to keep it [the turbo] at the rear for some good reasons.

"There is also no good reason to change it, as we don't see a lap time benefit from a car perspective. So, from where we put the elements and how we assemble them, they are where we like them to be.

"Now it is just a case of more continuous development, so we do the normal development. But it is also fair to say that the real emphasis is on the ICE [internal combustion engines] plus the turbo.

"That is what you do work on and that is what I guess Mercedes is doing. They are not spending that much time on the ERS system – they keep developing the ICE."

Matching Mercedes

Having been forced to focus more on sorting reliability than chasing performance over the early part of the campaign, Renault suspects it is currently around half a second adrift of Mercedes.

However, knowing what progress it has made on the dyno for future development, it has faith that over the remainder of the campaign and especially in to 2018 it has the possibility to match its German rival.

Taffin added: "It has been clear the target we have set within Renault, that 2018 was the year that we needed to be at the level of the benchmark, which is still Mercedes.

"We have done some part of the job this year and we will have to achieve the rest through the winter. Maybe we will start next year with a bit of a gap, but that is what we have to do next year.

"We have got engines on the dyno and we can clearly see that there is some progress, and we know there can be 0.3-0.5s difference depending on the track.

"So if Mercedes is still getting one or two tenths over next winter, we have got what we need to close the gap. Whether we will be in front by the end of next year we will see...but it is feasible. We've got what we need to do now."

Taffin says he is not surprised that Mercedes has kept its engine advantage in F1, because he thinks having got its concept right from the start it has not had to waste time reconfiguring its design.

"I still do think that we are making more progress than them, but we had to rethink what we produced for 2014," added Taffin.

"It could be that Mercedes had the right concept from the beginning and could build up from that. You know how complex these engines are, and obviously we sort of made a mistake in the first year and had to rebuild.

"We have this new concept now and are working on that – that is why it has taken some time. To be fair, Mercedes is still having the return from what they have been successfully having from year one.

"All in all, we have clearly seen that the gap is reducing a lot, so we could have thought that in year one [2014], the gap was one second, or even more. Now we are talking about tenths and we know it will be less than half a second for sure."