Wolff hopes Porsche will commit to F1 in 2021

Mercedes boss Toto Wolff says he would like to see Porsche join Formula 1 as a manufacturer in 2021.

The last time the carmaker was involved in F1 was in 1991 as an engine supplier for the Footwork team. However Porsche has been taking an active interest in the sport's latest discussions about its technical future.

The current engine specifications expire at the end of 2020 and Formula 1's commercial rights holders Liberty are in the process of coming up with a blueprint for what happens after that.

While Porsche has made no public commitment about returning to the sport, it's thought possible that they will partner with a team such as Red Bull or Williams.

If it comes off, Porsche could prove to be a major rival to Mercedes - but Wolff says that he is in favour of it.

"The more we can fight on our little playground, in the sandpit, the more we enjoy it," Wolff told Sky Sports F1 after Friday morning practice at the Red Bull Ring.

"I guess that Porsche's interested and looking at the environment, [but] it's not quite clear how," he said. "They are sitting on the table and giving their input."

Porsche's decision will depend on the details of Liberty's plans for the future of Formula 1. Current teams are expecting to hear more about those plans this week at a meeting of the sport's Strategy Group.

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"They are not cast in stone, but I guess next week in the Strategy Group we are going to hear a little bit more," said Wolff.

"It's still not agreed between what's been in the table in the past sessions and all of the engine manufacturers," he added. "So there are quite some tough discussions ahead, I guess."

Mercedes has been pushing to retain some of the current advanced hybrid technology, in order to keep F1 in line with the current move worldwide to electric cars and energy efficiency.

"For us it's important that the technology message is still there, in efficiency," Wolff insisted. "'Efficiency equals performance' is important when the whole world moves into green and electricity."

Wolff said that it would be a mistake if "we, for historic nostalgia, move 20 years back."

"It's not something that we want to do. It needs to stay on a very high performance and efficiency level," he insisted.

"It needs to be a different shade, and that is important for all us engine manufacturers, and not be a standard part."

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