Alain Prost has suggested that the time for Renault to switch their full focus to 2017 is now approaching.
The quadruple world champion, now an ambassador for the French carmaker and a paddock television pundit, hailed Renault for the improvements they have made to their power unit this year.
Prost was speaking in Monaco, where the Renault customer Red Bull were driven to pole by Daniel Ricciardo, who then only narrowly missed victory due to a pitstop bungle.
"This was an extremely fast turnaround" by Renault, Prost told French daily Ouest France.
"It's pretty rare that it happened in a very calculated world like Formula 1. It can happen with something like aerodynamics but not so often with the engine.
"It's good for the morale of the people working on the Renault project."
On the other hand, Ricciardo's Mercedes-beating pace in Monaco also demonstrated the shortcomings of the works Renault chassis, which is fitted with the same power unit.
"It showed all the work that Renault must do with the chassis," confirmed Prost. "Honestly, it's a very big task."
Team boss Frederic Vasseur has acknowledged that Renault have to work hard to get ready for 2017, but he also says that the 2016 chassis will not be abandoned as it may affect the 'competitive spirit' of the Enstone-based team.
"There is a choice to be made but it isn't mine," insisted Prost. "It's a management decision.
"It is not easy but at some point, a decision has to be made. The important thing is to build for the future. This is precisely what Mercedes did for three years and then took advantage of the change in regulations."
The season continues with the Canadian Grand Prix on June 12.
