Mercedes boss Toto Wolff says that progress is being made on Formula 1's new technical direction.
The current regulations expire after 2020 and negotiations are ongoing between teams, the FIA and the commercial rights holders as to the direction of the sport from 2021.
"The only major thing which we need to solve is that we are still spending a lot on engine development," Wolff said. "On most of the topics we have found an agreement."
Among the proposals is an end to the MGU-H unit, which has proved expensive to develop, and unreliable and problematic in use. Mercedes is opposed to ending the MGU-H but appears resigned to the decision being pushed through.
"We have given up on some of the standpoints," Wolff admitted. "We have accepted to lose the MGU-H. We think that the technology is a step backwards.
"Hybrid energy recovery systems have been on road cars, and they need to happen in F1 in my opinion," he said. "We cannot close our eyes to what's happening in the world.
"But in terms of achieving a compromise for the benefit of the spectacle, the 'H' going, the revs going up, the fuel limitations going, I think we will have a louder engine.
"Shocking your senses with an engine sound is maybe something that we can improve," he said. "I think on the engine regulations we're pretty close on being able to tick the box."
However, some areas of disagreement remain, despite an end of June deadline fast approaching.
"There's a discussion on dyno limitations," Wolff said. "We don't want to continue to outgrow each other with more infrastructure."
"I had a bit of a moment in the strategy group," he admitted. "One where I need to speak to my anger management psychologist!
"[It was] when we talked about getting rid of fuel flow limitations, all fuel flow allowances, and just open it up from the get go.
"It's not the most sustainable message we're sending out.But we can understand from a spectacle standpoint. It is something you need to consider and accept."
Most of all, Wolff said he is worried about investing in new engine technology while continuing to develop the existing power units.
"What we need to avoid is double spending over the next years," he said this week. "[We shouldn't be] continuing to develop the current engine, and then also doing the new one."
Renault boss Cyril Abiteboul has already proposed a freeze on engine development over the next two years so that attention can turn to 2021.
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