Renault's engine chief Rob White has said his company remains unhappy that its power units are still behind some rivals in the horsepower stakes.
The French car company has long campaigned for a move to equalize engine performance in F1, amid suspicions that some manufacturers have eked out more horsepower while the sport's engine freeze has been in place.
Although White acknowledges that only full dyno testing will prove how the engines in F1 compare, he reckons his outfit is definitely behind some of the opposition.
"I believe the maximum power of the Renault engine within the useful RPM range is not as good as the best of its competitors," he said on Tuesday. "Analysis of observed car performance supports this conclusion but it is impossible to accurately quantify differences in engine power except by comparison of power measured on the dynamometer.
"The reasons for this deficit are historical, resulting from engine developments undertaken during successive cycles of engine homologation. Changes to the engine have been restricted by the Sporting Regulations since the 2007 season, but the way in which the engine is used has changed greatly during the same period.
"For example, we have seen two reductions in maximum RPM, engine life has doubled, KERS was installed and removed, and refueling has gone. These changes have been handled by 'retuning' the engines and by allowing limited modifications.
"The engine suppliers have operated within these rules to develop the engines currently racing and, considering that the engines are all different, as are the internal constraints within the engineering teams, the outcome after a number of "open-loop" iterations is understandable. Of course, characteristics of the engine other than its power contribute to the performance of the car teams. Driveability, heat rejection, weight and installed stiffness are significant, but overall car performance is most sensitive to engine power.
"Renault is committed to supply fully competitive engines and we are confident that this is possible within the current rules framework administered by the FIA, but we cannot be satisfied while the power of our engine remains significantly behind the best."
White also said that there was not likely to be any imminent announcement about a fresh customer supply deal for Renault, despite continued speculation linking the company with Lotus.
"We have an excellent relationship with Red Bull and we hope to continue to build on it for the future," said White about Renault's customer supply deal situation for 2011.
"We have the capacity to supply additional teams in the future and would be willing to do so if it was good for Renault and for the sport as a whole. We would maintain our policy to supply strictly the same performance specification to all Renault powered cars. There has been speculation in the press, with different teams mentioned from time to time, but no announcement is imminent."