2014 engine rivals Renault and Ferrari appear unlikely to close the gap to dominant Mercedes before the start of next season.
The struggling marques pushed hard for the current development 'freeze' regulations to be relaxed ahead of 2015.
But Andy Cowell, the engine boss at Mercedes, insists there is no good reason for the German carmaker's rivals to be complaining about the current rules.
"The situation is clear," he is quoted by Spain's El Mundo Deportivo.
"You can develop the engine all year long and then race your great evolution at the beginning of next season.
"There is a very long list of development opportunities for our opponents to take a big step forward," he added.
But according to Germany's Auto Motor und Sport, Renault and Ferrari are now running out of time to prepare meaningful upgrades to their 'power units' before 2015.
The report said neither engine maker even looks set to use all the available 'tokens' of allowed performance upgrades by the end-of-February freeze deadline.
"They started to develop their 2015 engines too late," said Auto Motor und Sport.
A baffled Mercedes team chairman Niki Lauda said: "Why didn't they start already in Melbourne, when they knew how far behind they were?"
The report said Renault, for instance - although now enjoying the input of engine guru Mario Illien - has run out of time to mimic Mercedes' components layout.
We know we cannot reach Mercedes' level, but we want to be closer.
Auto Motor und Sport said Ferrari, on the other hand, will enter the 2015 season with a more Mercedes-like layout.
But the boss of Renault's works team Red Bull, Christian Horner, sounds defeated already.
"We expect a slight increase in performance," he is quoted by El Confidencial. "We know we cannot reach Mercedes' level, but we want to be closer."
New era would not be easy
Ferrari is also expecting 2015 to be another struggle.
Reports suggest Mercedes' engine chief Cowell turned down an offer to switch to Maranello, while Ferrari's designer Nikolas Tombazis is understood to be close to the exit.
New Ferrari driver Sebastian Vettel described his first taste of a red cockpit as "magical" on Saturday, but others are more realistic.
"In the midst of all this euphoria," a Ferrari engineer told the insider Leo Turrini, "we should not forget to apologise in advance to Seb and Kimi for the car they will drive in 2015."
It has emerged that Kimi Raikkonen will have a new race engineer for 2015, but fellow Finnish champion Mika Hakkinen remains worried about his countryman.
"I watched Kimi in Abu Dhabi," Hakkinen said in his latest interview for sponsor Hermes, "and I could see that he had no pleasure of driving.