Toto Wolff has said that he thinks 2018 is a year of truth for Formula 1's new owner Liberty Media.

The Mercedes boss said that the sport's new American regime had a "grace period" last year.

"It's always easy to criticise the coach from the stands, because making decisions is not always easy," Wolff told Stuttgarter Nachrichten newspaper.

"But in my view not all the decisions were positive."

Wolff said that banning grid girls is one mistake, and also questioned whether Liberty can follow through on its promise to introduce exciting new grands prix.

"Hopefully we see something like New York, San Francisco, Miami or an attractive European or Asian race," Wolff said.

"I hope to see it in the second year. Only then will it be fair to judge Liberty."

Wolff says that he misses ousted F1 supremo Bernie Ecclestone in some ways.

"In his prime, Bernie was brilliant at pulling off a big deal," he said.

"If he went to a government and said he dreamed of a Singapore Grand Prix, that's what happened. The current management has to show that it can do that too."

Wolff said that Liberty's efforts to please everyone has also created problems.

"Now that Bernie is gone, Liberty is struggling with the problem that suddenly there is a promoters association for the circuits. Everyone wants to renegotiate their deal," he said.

As for what will happen in 2018 from a competitive point of view, Wolff answered: "I'm not good at reading a crystal ball.

"But from the tests I can only derive that on one lap, there is relatively little between Ferrari, Mercedes and Red Bull."

The new season gets underway next weekend with the Australian Grand Prix.