Renault admits it will start 2015 F1 season with work still to do

The French manufacturer has set a goal of halving the deficit to F1's pacesetting team before the first grand prix of 2015 in Australia.

After encouraging work on reliability, through a number of race runs with Red Bull and Toro Rosso at the first Barcelona pre-season test on February 19-22, Renault switched to performance work at the Circuit de Catalunya last week.

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It brought upgrades to Spain, but these introduced some new driveability difficulties, which Renault admits it still has not fully solved.

Renault head of track operations Remi Taffin said: "We were able to get the potential of it [the engine], but the main thing we are still working on is to try to get it as consistent as we can, and on driveability.

"We did not achieve all the work that we would like to do, just because we could not get all the parts in one go. That was part of how we tried to push on before we get to Melbourne.

"Just to make it clear, to map an engine is not a case of two or three days. We're talking about weeks or sometimes months, especially with this power unit."

Taffin said Renault was happy with the final specification of engine it would take to the first race, but admitted it would take several grands prix to unlock the potential.

"We can clearly see the potential," he added.

"Sometimes you measure something on the dyno and then you go on track and you can't really find what you've seen. That's not the case. We can clearly say the improvement is there.

"The main things we've got left - not actually a problem, just a matter of time and achieving that - is to make it much more consistent, much more available, much more driveable."

When asked how much progress Renault could make before arriving in Melbourne, Taffin replied: "It's very difficult to say. We've got our programme going on, so if the question is whether we will be 100 per cent on top of everything, I don't think so.

"We will still need to work on that. Each race will be a sort of step for us. That's where we are."