Renault says the loophole in the regulations that allows for engine performance development throughout the season partly had a negative impact on its plans for this year.
Ferrari highlighted the loophole at the end of last year, which allows engine manufacturers to work on performance throughout the season rather than have it frozen just ahead of the first race as was initially intended by the FIA. Put simply, the manufacturers were given a whole season to spend their 32 performance tokens on updates rather than rush through the updates ahead of the first race.
Ferrari described the FIA's concession on token spend as its first victory of 2015, but for Renault the uncertainty ahead of 2015 meant it was actually hampered by not knowing what approach to take.
"We've been aggressive over the winter, but I think we have not really been assisted by the regulations," Renault Sport F1 managing director Cyril Abiteboul told ESPN. "You may remember that there has been a lot of - not confusion - but hesitation on whether the regulation on token usage would change or not and therefore at some point we had to be prepared to use the 32 tokens for race one and then it changed, changed again and only on December 16 I believe was when we got confirmation that in-season development would be allowed. It's not the best conditions to prepare the type of programme that we had to prepare."
Renault spent fewest tokens over the winter, using 20 compared to the 22 of Ferrari and 25 of Mercedes, meaning it has the most left to spend over the course of the winter. Chassis partner Red Bull suggested after the first race that Renault had actually made a "retrograde" step with its developments during the close season, but Abiteboul said that analysis is unfair.
"Could we have made better use of the tokens, basically value for money of the tokens that are used and the money that is spent? Maybe. I think there is nothing that regulates the lap time benefit that you get out of a token, but it is completely incorrect to say we are behind in terms of power.
"Mercedes, by the way, have not stood still. They have used 25 tokens to our 20 tokens, which means that they have made even more changes to the engine than we have made. That's the thing, Red Bull should realise that if we had not used those tokens correctly then we would have been further away from Mercedes."