Red Bull have questioned the FIA's conclusion that engine performance has now been basically achieved in Formula 1.
Germany's Auto Motor und Sport reports that, after the opening three races of 2017, the governing body analysed data that shows the gap between Mercedes, Ferrari and Renault is within an acceptable three-tenths per lap.
The report ties in with speculation that straggling Honda may be given some help to catch up.
Sergio Perez, a Mercedes-powered Force India driver, agrees that engine parity between the top three manufacturers is close.
"Ferrari has caught up and Renault is not far away," said the Mexican.
Yet Renault-powered Dr Helmut Marko has questioned the FIA's methodology of having analysed the performance of the three engine makes over a series of laps.
"Probably the in and out laps," he said sarcastically.
As for Perez's claim that Renault has basically caught up to Mercedes, Marko told Auto Bild: "That's what he said probably because [Renault's] Nico Hulkenberg was faster in Bahrain than he was."
Indeed, Marko may be referring to speculation that Hulkenberg - as the works Renault team's top driver - is getting the pick of the French-made engines.
"These speculations cannot be dismissed," said the Austrian.
The championship continues tomorrow with the Russian Grand Prix.
