FIA president Jean Todt has warned Formula One bosses not to "undervalue" its current manufacturers in the search for new ones.
Three of F1's four manufacturers -- Mercedes, Ferrari and Renault -- have criticised the engine proposal put forward for the next regulation cycle, which will start in 2021. The blueprint suggests simplifying the current V6 turbos in a bid to become more appealing to manufacturers previously put off joining the sport.
Ferrari has threatened to quit after 2020 if the proposal is not altered, while Mercedes and Renault have also spoken out in opposition. Todt, who has just been re-elected to a third and final term as president of the FIA, thinks F1 must find a compromise which suits existing and prospective participants.
"What I feel would be unfair would be to undervalue the existing engine suppliers involved, and listen to those who may think they will come," Todt said. "For me, it is important in light of the existing situation to see what will be the best evolution of the engine for the future, but by respecting the investments of those who have made the investments so far."
Though Todt admits the current V6 turbo engines have their flaws, he is happy the post-2020 proposal was for an adaption of existing technology rather than a complete re-think of engine concepts.
"Clearly if you ask me what I feel about the engine - it has been one interesting exercise. I think it is too complicated. I think it is too expensive. But it is probably a very good first step to go to a next generation of engine, which will be one evolution from what we have now.
"I am against starting on a completely new development of engine but I think we should take what we have understood with this engine and allow the actual manufacturers who have been investing heavily to be able to enjoy what they have been investing for the next generation of engine, and also encourage newcomers to come."