Mercedes have joined Ferrari in threatening to quit Formula 1 after 2020.

Earlier, Ferrari president Sergio Marchionne said that if Liberty Media proceeds with its plans for the 2021 engine rules and budget cap, the Italian team could withdraw and race elsewhere.

Now, Mercedes boss Toto Wolff has admitted that he is not happy at the end of Liberty's first year in F1.

"Nothing," he said when asked by Kronen Zeitung newspaper to point out a Liberty-inspired highlight of 2017.

"Doing erratic actions like Michael Buffer in Austin does not make the sport any better."

When told that Liberty just wants closer racing, a better engine and cost controls, Wolff responded: "But we do not see any vision.

"Nobody knows where the journey is going. All we know now is that sales and profits have fallen sharply."

Asked if Mercedes could join Ferrari in their F1 quit threat, Wolff said: "Such a scenario is quite conceivable. Just as it is for Ferrari.

"If we do not see what Formula 1 stands for, then we have to ask ourselves the difficult question: not if but where do we want to operate in motor sport at the highest level?"

Earlier this week, FIA president Jean Todt and F1 chief executive Chase Carey played down Ferrari's quit threat.