Renault team principal Cyril Abiteboul says the French manufacturer's gains on the power unit have been made clear with recent performances in Belgium and Italy.
Daniel Ricciardo and Nico Hulkenberg qualified sixth and seventh at Spa-Francorchamps, but were dropped back down the grid by engine penalties, with Hulkenberg recovering to the points.
Monza was a happy hunting ground for the red team, Ricciardo and Hulkenberg lining up fifth and sixth on the grid and gaining a place each by the chequered flag thanks to Sebastian Vettel's shocker.
Much scrutiny was put on Renault's engine this year after Red Bull's decision to ditch them for Renault, but Abiteboul believes the critics have been answered.
"I think it's really fair to say the job done on the engine side is very clear," said Abiteboul.
"We were competitive in Montreal, in Spa, in Monza, which means the demonstration is clear.
"The weaknesses of the car are still here – that's why I'm not overjoyed because I know there still will be tough times ahead of us in the season but this is just a demonstration of the strengths, which have been clearly exposed [in Italy]."
Renault began the year targeting a season which would see them close the gap to the big three teams on the grid, but they will instead look to overhaul fourth-placed McLaren over the closing months of the campaign.
Abiteboul added: "It's been bumpy this year. There have been a number of occasions where we could have had a decent result with some points and helping for the championship, and that has not happened for many different reasons and sometimes for our own cause, sometimes external factors. [In Italy] nothing has gone against us, against the result.
GPFans is a multi-platform, multi-language brand dedicated to Formula One coverage. We bring you all the ins and outs of the sport, 24/7, everything from up-to-the-minute news and features to the latest viral stories and clips.
We believe that a new generation of exciting, outspoken drivers will make F1 more popular than ever before, and we want to give our users access to as much of their heroes as possible, on and off the track. From Lewis Hamilton to Max Verstappen, Daniel Ricciardo to Sebastian Vettel, we provide in-depth analysis of every every Grand Prix in the season, from Australia to Abu Dhabi.
With Formula One under the new ownership of Liberty Media, how the sport is being covered is evolving, and GPFans will look to be at the heart of this progression into new media, as one of the fastest-growing sites covering the king of motorsports.