FIA regulations are too unclear for the sanctioning body to be forcing teams to freeze engine development.
F1 newcomer Honda has been left out as rival engine suppliers prepare to develop their turbo V6 power units throughout the 2015 season.
It has emerged in recent days that, because the wording of the regulations is unclear, the sport's 2014 suppliers Mercedes, Renault and Ferrari do not in fact have to present in Melbourne an engine to be 'frozen' for this year's entire world championship.
"Everything depends on the interpretation of the rules," Mercedes team boss Toto Wolff told Italy's La Gazzetta dello Sport earlier this week.
It is believed the loophole was discovered by Ferrari, and then backed in subsequent meetings by fellow engine straggler Renault.
"The FIA offered its version (of the rules interpretation)," Wolff added, "and I do not see any problems.
"Certainly the freezing of engines in February is best for those who are at the front," said the Mercedes chief, whose Brackley team utterly dominated last year, "but we are able to develop too."
What's good for the goose...
Crucially, however, F1's engine newcomer Honda will not be able to develop throughout 2015.
That is because the rules make clear that, for new engine suppliers under the turbo V6 rules that were implemented in 2014, a clear start-of-season homologation date is set: 28 February.
No such homologation date exists, however, for engine suppliers' second year under the new rules.
It means Mercedes, Ferrari and Renault can deploy their 32 performance development 'tokens' throughout the entire 2015 season. Honda cannot.
Writing in Germany's authoritative Auto Motor und Sport, highly respected correspondent Michael Schmidt said: "Newcomers (like Honda) have no tokens in the first year.
"Until their engine is homologated at the end of February, they are completely free to develop, but after that they may only upgrade on grounds of reliability, cost or safety," he explained.
Schmidt continued: "McLaren boss Ron Dennis already expressed his concern at the recent Strategy Group meeting that the rules discriminate against his new engine partner."