Mercedes believe Liberty Media had the wrong focus with their planned rule changes for Formula 1 in 2021.

The sport's owners want to introduce a sweeping overhaul of much of the current structure, both sporting and commercially, ranging from engines and car design to a budget cap and revenue distribution.

All of this was with the ambition of attracting more manufacturers back to the grid and hopefully having independent suppliers for teams such as Red Bull, McLaren etc. to be competitive against the likes of Mercedes and Ferrari.

"We should be happy with four premium manufacturers committed to the sport," Mercedes motorsport boss Toto Wolff argued to ESPN recently.

"[The ones that are] already in there for a long time and trying to make sure that, foremost, we seek compromise with the loyal partners in there [should come first].

"Then we look at the ones who might join in the future and listen to them but that is only the second priority."

Names like Aston Martin, Porsche and Cosworth were all linked with possible interest in the 2021 engine rules, which initially saw ideas for an additional turbo and the removal of the MGU-H part of the ERS in an effort to reduce costs and increase sound.

Since their interest waned though, the planned changes have been watered down but Wolff remains dismissive of Liberty's position adding: "You want more than four [manufacturers]? What do you want, five or six?" he asked. "Where does that thinking come from? Is it greed?"

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He also warned that the current ideas being proposed are still going to incur big expenses for the four current engine makers.

"We have demonstrated to Liberty and the FIA that redesigning an engine is going to spiral the costs out of control," Wolff explained.

"Even this [proposed 2021] engine now - which has more revs, more fuel flow, more fuel allowance - will result in enormous costs. Ideally, we would have liked to stay where we are, and not touch it.

"Engine performance is converging," he continued. "The engines are not far away from each other.

"[But] every time the regulations change, you're going to have a wider spread between the best and the worst. So why do we change it?"