Jan.5 (GMM/Inautonews.com) Delaying a start-of-season engine ‘freeze’ may be nowhere near enough for Mercedes’ rivals to catch up in 2015.

Although the rule ‘loophole’ championed by Ferrari and Renault will now allow them to develop their turbo V6 engines beyond February 28, it will also apply to Mercedes, F1’s dominant champions of 2014.

“We’re not going to give up,” Christian Horner, boss of the Renault works team Red Bull, is quoted by Russia’s f1news.ru.

“But given the size of our deficit, as well as the fact that Mercedes are going to develop as well, significantly reducing the gap in 2015 is going to be difficult.

“If you believe the rumours,” Horner added, “there is a risk that not only will the gap not be reduced, but it could even get bigger.”

Indeed, Germany’s Auto Motor und Sport reports that Mercedes’ engine division at Brixworth has uncovered a further 50 horse power boost for 2015 over and above the German marque’s dominant ‘power unit’ of last season.