The loss of Robert Kubica has hurt Renault's ambitions for 2011, according to the always-blunt Niki Lauda.
With Kubica recovering from horror injuries in a pre-season rally crash, Renault turned to the German veteran Nick Heidfeld to become Russian regular Vitaly Petrov's new teammate.
"Renault have had a good car from the beginning but the team is being limited to some extent by its drivers," triple world champion Lauda told the German broadcaster RTL ahead of the Turkish grand prix.
"They are doing a good job but when you are looking for that last little bit from your car you do miss the top drivers," he added.
The 62-year-old gave a similarly forthright view when asked about the proposed four-cylinder engine rules for 2013.
If the new engine comes they need to think about how to make them loud enough
"I've thought about it and don't understand why there are always smaller and smaller engines. It is expected that in Formula One there is a lot of power for high speeds and with a noise level that everyone wants," he said.
"Now if the new engine comes they need to think about how to make them loud enough."
As for rumours CVC could sell F1 to a bidding consortium, Lauda answered: "CVC is an investor, so it's natural that they buy cheap and after a period of time they sell. But I don't know anything about it so I can't comment."