Cape Town - Renault F1's managing director Cyril Abiteboul has warned Formula 1 that "untenable" rising engine costs could see one of the four manufacturers drop out of the sport.
Although Formula 1 owners Liberty Media have been speaking for the past year about a cost cap, the price of competing in Formula 1 continues to rise.
One of the biggest costs for the manufacturers - Renault, Ferrari, Mercedes and Honda - are the engines.
Unless something is done to curb that, Abiteboul fears the sport could lose one of the four in the years to come.
He cited Honda's 2018 gains which came with a "huge investment" as cause for corner.
"It is not a surprise because it was very clear last year already that Honda were making very rapid progress," Abiteboul told Autosport.
"Reliability was not there last year, but it was extremely clear, and I remember in Spa, there was a very clear signal that Honda was on the move given the huge investment which we understand that Honda is putting in.
"It is not a surprise that this is paying off because we are still in
an F1 that is rewarding how much you are spending rather than how you
are spending it," he said.
"And that is a concern. That (rising cost) is in my opinion untenable.
"It may be paying dividends for Honda now, but at some point it will
be untenable for one of the four - and who knows what will happen then," he continued.
"I think F1 cannot afford to lose one of them. And I don't see enough decision/action being taken to alleviate that necessity to spend in a way that might be untenable in the medium to long term."
Abiteboul added that Honda's improvements will force Renault to invest heavily as they try to stay ahead of the Japanese manufacturer.
"They are definitely back. They are at a similar level to us in terms
of competitiveness this year because of our decision on Spec-C. That is
why again we cannot sleep on next year's engine development," he said.
"And we also need to put that in perspective of 2021, where we want to start as early as possible. As always we need to see how we can balance short term objective with long term objectives."