Adrian Newey, the fabled designer of Red Bull's troubled RB10, expects the 2014 season to be dominated by the new powertrain rules.
At Jerez last week, the reigning world champions struggled even to run the new car due to problems mating the Renault V6 and related energy-recovery technology with Newey's famously extreme aerodynamic packaging.
"At least in the early part of the season," Newey is quoted by Italy's Autosprint, "we will be talking about an 'engine formula'.
"Reliability, power, fuel consumption -- they will be decisive factors," he added.
"The aerodynamics will only really count once these new V6s have matured.
"But it has to be said that we are relying on the 'power unit' not only on Renault -- there are many other suppliers.
"And each of them will have to adapt to the development speed of modern formula one," said Newey.
The 55-year-old Briton is undoubtedly the most famous technical boffin in the F1 paddock, and he said preparing for 2014 was "the biggest challenge of my career".
"We had a small amount of time for such a complex car," he admitted.