Ferrari F1 team cautious on Mercedes engine unfreeze stance

The three current F1 engine manufacturers - Ferrari, Mercedes and Renault - met during last weekend's US Grand Prix to discuss fresh proposals to relax rules that prevent them introducing updates during the season.

Mercedes suggested it may be open to allowing a one-off mid-season upgrade in 2015, having previously blocked attempts by Renault and Ferrari to allow in-season development of engines, claiming such developments would substantially increase costs.

Both Ferrari and Renault deny costs would increase substantially were the engine freeze relaxed, which has led Mercedes motorsport boss Toto Wolff to suggest Ferrari needs a new calculator if it really believes this is the case.

Ferrari team principal Marco Mattiacci said he welcomed "constructive" negotiations in Austin, but urged caution given that Mercedes has changed its mind before on this issue.

When asked by AUTOSPORT whether he was optimistic Mercedes could be prepared to cede ground on the engine freeze rules, Mattiacci replied: "They were in Singapore too, so I would wait.

"We're working in a very constructive climate.

"Niki [Lauda, Mercedes non-executive chairman] did a fantastic job to pull everyone around the table so I appreciate [that].

"The climate was very positive, but again my expectations are very well managed considering the past."

RED BULL ENCOURAGED

Red Bull boss Christian Horner has also previously criticised Mercedes for making a U-turn on plans to lift the engine freeze.

He told reporters after the US GP that he was more encouraged by discussions in Austin, but that wholesale changes were unlikely given the current costs debate in F1.

"Mercedes participated in a constructive discussion - they haven't agreed to anything yet but there was a very constructive discussion, which hopefully sees a solution in place in the very near future," Horner said.

"Mercedes have accepted they need to provide a window of opportunity to the others to introduce competition, but I cannot see beyond that any real change in technical and sporting regulations.

"Any time you change rules it has a detrimental effect on costs."