Dominant 2014 champion Mercedes thinks its rivals can catch up.
Germany's authoritative Auto Motor und Sport on Thursday estimated the marque's advantage last year at as much as 60 horse power.
Many believe that is too great a gap to bridge in just one winter, but Renault has worked hard on its structure and engine, Ferrari set the test pace at Jerez and newcomer Honda is famous for having dominated F1 in the 80s.
Mercedes engine boss Andy Cowell agrees: "The rules of physics and chemistry are the same for us all.
"I see no reason why the competition cannot build an engine as good as ours.
"Of course we do not stand still, but the higher you are in your development, the flatter the curve is to improve," he told the German publication.
Cowell also said Mercedes' rivals have the advantage of being able to see exactly where the German giant is strong.
"Thanks to GPS measurements, they know the areas they need to look at, so Ferrari and Renault just have to aim higher. That is their advantage.
"Honda is a bit of an unknown, but we should not underestimate them. We will take a big step forward, but I cannot guarantee that it will be enough to be better than the competition," he said.
Finally, Cowell commented on Bernie Ecclestone's desire for 1,000 horse power engines, even though the new turbo V6 era is only a single season old.
"I believe that with the current architecture, we can achieve that (1,000hp), and produce more sound, if we increase the fuel flow rate," he said.
"However, we should not dilute the concept of energy efficiency. Technology transfer from motor sport to the road industry is important for formula one. It's why Honda came back," Cowell argued.