Mercedes' current big advantage in F1 has prompted calls for sweeping change to the power unit regulations, and Bernie Ecclestone has even suggested the idea of a power limit to stop the best engines being developed any more.

That radical idea has not gone down well with Mercedes nor Ferrari, who feel it would be wrong for them not to be allowed to keep developing their engines.

Mercedes has since admitted that it would be open to freeing up the rules a little – such as allowing in-season development again in 2016, if Renault and Honda needed it.

"If it is what the others need, or what they believe they need, in order to catch up then we will certainly consider it," said Mercedes motorsport boss Toto Wolff at the British Grand Prix.

Right balance

McLaren racing director Eric Boullier agrees with Wolff that it would be wrong to stop Mercedes development, but equally he feels that engine manufacturers who are struggling need some help.

"I agree with Toto, we cannot hurt the DNA of F1," Boullier told Motorsport.com. "But this is a competition and we need to allow people to compete.

"I think we need to maybe change a little bit the rules to allow everyone to be a bit more competitive.

"Then you will be better or someone else will be better, but at least you have a chance to compete."

Red Bull boss Christian Horner, whose outfit has faced difficulties with Renault, says all options should be considere, but allowing more tokens in-season would make most sense.

When asked for his feelings about a power cap, he said: "It is mixed. In some ways, it would seem the sensible thing to do – but in others it takes away the element of competition.

"So I think the right thing is to allow the tokens to allow the teams that are behind the chance to keep developing.

"I also think it would be difficult to do, to actually cap. But it is an interesting concept which we should certainly look at."