Mercedes boss Toto Wolff believes Formula 1 should be doing more to promote the benefits of hybrid engine technology.
His comments come at a time of fresh doubt for the future technical direction of world championship in the wake of Honda's decision to stop supplying power units to Red Bull and AlphaTauri at the end of 2021.
The Japanese manufacturer cited its commitment to a carbon neutral future as being behind the decision to pull out, although the cost of developing the complex hybrid technology used by F1 will surely have been an additional factor.
It leaves F1 with just three engine suppliers. Mercedes sells customer units to Williams and Racing Point while Ferrari powers Alfa Romeo and Haas. Renault currently provided engines to McLaren, but they will switch to the Mercedes camp next season.
Mercedes has dominated F1's recent hybrid era, and Wolff is disappointed that the sport has not done more to help promote the technology as a whole.
"I believe we are not telling the hybrid story well enough," he told Autosport magazine. "We are a pretty good showcase for hybrid technology."
In particular, Wolff praised the current power units for offering "50 per cent thermal efficiency".
He also singled out "the complexity and technology that exists in these cars with the energy recovery with kinetic energy or exhaust gases, the batteries that we're using and the technology within them" as key selling points.
"We’re still lacking the messaging that these engines are fantastic hybrid technology, but they’re much too expensive," he acknowledged.
The current engine regulations are due to last until 2026, but Honda's departure - and the lack of any interest from other engine menufacturers to come into F1 - had prompted calls for this to be be brought forward.
“When you look at the costs involved in the engine supply, they are enormous," Red Bull boss Christian Horner explained. "That is why F1 has failed in its attempt to attract new engine suppliers and new manufacturers into the sport.
"Honda’s withdrawal is a real shame for F1, but also a real wake-up call.”
The question is what direction the next generation of engines will go in. With road cars increasingly phasing out petrol-powered combustion engines in favour of electric vehicles, F1 could soon end up converging with Formula E.
"The next generation of power units, whenever they come, will lend even more to sustainable energy recovery and sustainable propulsion systems in the future," Wulff suggested.
"We know now that we have to look at the costs," he acknowledged. "We don't want to make the same mistake that we are purely engineering driven like with these power units.
"But [we must] make sure they are something innovative, sustainable, powerful, fuel efficient - and at a reasonable price."
Mercedes could clinch its seventh consecutive constructors title this weekend at the Portuguese Grand Prix, although it remains a somewhat unlikely scenario.
With six races still to go, Mercedes have 391 points compared to Red Bull's 211. It means if Lewis Hamilton and Valtteri Bottas finish in the top two, then their main rivals would need to pick up at least five points between them to keep the championship alive.
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