Ralf Schumacher admits he has concerns about Audi's Formula 1 ambitions.

The Volkswagen-owned carmaker has fully acquired Swiss-based Sauber and will rebrand as the works Audi team from 2026.

"They have an excellent driver already in Nico Hulkenberg, but they also have a free cockpit," former F1 race winner Schumacher told Sky Deutschland.

Indeed, Audi made significant efforts to sign the available and seat-hunting Carlos Sainz, whose father has close ties to the German marque, but it is believed the 29-year-old sees more potential in Williams.

Schumacher says he shares Sainz's apparent concerns about the Audi project.

"Audi does not seem to have managed to convey interest and self-confidence," he said. "The engineers are currently a bit stuck, but so are the drivers.

Now they have to build up the team," said the German.

"I'm excited about that, but they have to be very careful that it doesn't go the same way as BMW-Sauber did. Back then, Sauber's core team stuck together, which annoyed BMW and they abandoned the whole project."

Sauber officials recently admitted that their main concern with the current Concorde Agreement talks is ensuring the team is given a slightly higher budget cap to offset the higher cost of operating from Switzerland.

"I think for teams like ourselves it will be important to introduce an element that can, let's say, equalise differences in terms of cost of life," confirmed team representative Alessandro Alunni Bravi.

Ralf Schumacher agrees that Sauber's Hinwil-based headquarters is a significant issue.

"The main problem for Audi is the team's location," he said.

"Motorsport takes place in England - and persuading the engineers' families to come to Hinwil in Switzerland is not easy. I think the team is having a hard time recruiting new people," said Schumacher.

"I would like to see more aggression in what is going on with Audi."