Media reports in Italy suggest Ferrari boss Marco Mattiacci may have pulled off a political masterstroke over the US GP weekend by convincing F1's dominant force to agree to a relaxing of the development homologation rules.

But listening to Mercedes bosses Toto Wolff and Niki Lauda, it is difficult to imagine that is true.

We would not allow that, it is irrational and senseless. Niki Lauda

"They're saying they want to develop the engine during the year," Wolff is quoted by Frankfurter Allgemeine Zeitung newspaper. "I think this is an incredible nonsense.

"It just costs a lot more and the order would not change."

Lauda, the German team's chairman, agrees, estimating the additional cost per manufacturer of expanding the engine 'freeze' as at least EUR 10 million.

"We would not allow that," he is quoted by Italy's La Repubblica. "It is irrational and senseless.

"Ridiculous," the F1 legend continued to charge. "Mercedes wins its first title for 100 years and they want to change the rules.

"Ferrari can still work on 48 per cent of the engine. There is nothing to defreeze," said Lauda. "It's already thawed."