Boss Cyril Abiteboul has admitted Renault was about 60 horse power down on dominant 2014 title winners Mercedes last year.
"We estimate the gap between our engine and that of Mercedes at the end of the season to be about 60 horse power," he revealed to the broadcaster Canal Plus.
But Renault and also struggling Ferrari won a crucial political battle over the winter and can now work on their turbo V6 'power units' throughout 2015.
Abiteboul said: "We hope to close the gap by half, from the start of the season in Melbourne.
Starting 2015 with new engine
"Unlike Mercedes, we will start with the 2015 version of our engine, which is the same for Red Bull and Toro Rosso," he added.
"To date, we have used about two thirds of our allowed (32) 'tokens' to develop our engine this year. Our goal is to win at least five races this season," said the Frenchman.
In 2014, works Renault team Red Bull's Daniel Ricciardo was the only non-Mercedes driver to win, getting to the chequered flag first three times compared to Mercedes' 16.