Mercedes team principal Toto Wolff has defended his team in the wake of speculated drama. (Reuters: Evelyn Hockstein)

Mercedes boss Toto Wolff has accused rival Formula 1 manufacturers of ganging up on his team to put pressure on the governing FIA to change the engine rules, but said it would make no difference.

The Austrian was speaking at pre-season testing in Bahrain on Thursday, a day after the FIA announced an e-vote proposal to close a suspected loophole by proposing a change from August.

Rivals have accused Mercedes, who supply four teams, including champions McLaren, of exploiting a grey area to gain performance through compression ratios and thermal expansion of engine components.

The compression rate in each cylinder of the 1.6-litre V6 hybrid turbo engines has been limited to a 16:1, down from 18:1 under the previous set of rules.

But the current rules, specifically Article C5.4.3 of the regulations, say compression ratios will be tested “at ambient temperature”.

Mercedes is rumoured to have circumvented this rule by reportedly using materials that can expand in high temperatures, increasing the compression ratio of the engine, but will pass the inspection when cooled down.

The e-vote, which will be settled next week, is to change the rule from August 1, stating that the testing of compression ratios will be done in ambient conditions and at an operating temperature of at 130 degrees Celsius.

Wolff told reporters that the pre-season favourites would accept the rule change, but questioned the way it had been introduced.

“Either we stay with the regulations like we are, or the e-vote goes ahead on Friday with the proposal that came from the FIA. Both are OK for us,” he said.

“We said all along that this looks like a storm in a teacup.

“It doesn’t change anything for us, whether we stay like this or whether we change the new regulations. We also want to be good citizens in the sport.”

Wolff said he could understand the concern if the performance numbers being put around were close to the truth.

“If you have four other PUs [power units] that are putting immense pressure on the FIA at a certain stage, what choice do we have than not to play?” he asked.

Ferrari, Audi, Red Bull and Honda are the other power unit providers, with all facing a big challenge this season as Formula 1 starts a new engine era.

“You’ve developed a component to the regulations and that’s been confirmed and then everybody else gangs up and says it’s illegal. The regulators are being put under pressure. Is that how it should go?” Wolff said.

“Philosophically, I disagree. But that’s what has happened the last 50 years in Formula 1 and this time we were on the receiving end. I guess the next time, maybe we will be ganging up against somebody else because we believe it’s not right.”

There has also been media speculation that Mercedes has had a problem with certifying their 100 per cent sustainable fuel, but Wolff said those reports were wrong.

“This is another of the stories. We were told compression ratio is something that we were illegal [with], which is total bulls**t. And now the next story comes up that our fuel is illegal,” he said.

“Maybe tomorrow we’re inventing something else.”

The season starts in Australia on March 8.