Renault cannot approve of Liberty Media's vision for the 2021 engine formula until other aspects of the future are also clear, according to Cyril Abiteboul.
The Renault team boss joins Mercedes and Ferrari in currently opposing the plan for substantially different engines.
"What we have been presented with is a new engine," he told Auto Motor und Sport.
"That means a new development, a new project, probably more people, more investment.
"The second problem is that we don't know what Formula 1 will look like in 2021. The chassis, the cost reduction measures, how the money distribution changes - we don't know the whole picture.
"We have the engine concept but we can only judge that when the other puzzle pieces are together."
A key element of Liberty's engine vision is the removal of MGU-H, but Abiteboul said that is actually "an unknown".
"From today's perspective I have to say I don't like MGU-H," said Abiteboul. "But by 2020 we will have our problem under control.
"Then it will be cheaper for the manufacturers and the customers, and yet everything will start again at zero with a new engine concept.
"And there will again be manufacturers who will find the right and the wrong solutions, dividing the field into two groups again. Therefore, I see no reason to deviate from the existing concept."
The current world championship draws to a close this weekend with the Abu Dhabi Grand Prix.
