Renault's chief technical director Bob Bell believes they are heading in the right direction to match Mercedes in terms of its engine power.
Managing director Cyril Abiteboul recently revealed his optimism about the progress being made, and now Bell has echoed the sentiment ahead of the RS.17 launch on February 21.
"It's certainly behind Mercedes, there or thereabouts with Ferrari, maybe slightly off but not by much," Bell told Autosport.
"Renault has closed the gap to Mercedes. You only have to look at Red Bull's performance last year, they've been able to take the fight to Mercedes on many occasions.
"If nothing else that indicates not only a very good chassis but the engine has moved on a lot."
But Bell also warned that it may be another year before Renault's full potential is realised.
"We have to close that gap and we'll make another step over winter," he added.
"But whether that will see complete closure or not, you just can't tell. There's no way of knowing.
"We believe we can, given time. It might possibly not be this winter but certainly by the end of next year and into 2018, we ought to be right on it."