Formula 2 regular de Vries made an appearance for Audi at the Jerez young driver test last year, and was nominated as the manufacturer's reserve driver for last month's Moscow round.

The 22-year-old Dutchman was on standby for an injured Mike Rockenfeller following the German's heavy crash at the Norisring, although he was eventually cleared to race.

De Vries also joined Audi last weekend for his home event at Zandvoort, where he attended technical debriefs and drove the race taxi.

"We had him at the young driver test last year, he impressed us with his performance, and his approach to the whole thing," said Gass of de Vries.

"That was the reason we contacted him for the reserve driver role in Moscow, when we didn’t know whether Mike would be able to drive or not.

"That’s basically where the current contractual relationship ends. He was here this weekend [in Zandvoort], but he was more here to visit than having a proper role within the team."

On whether de Vries could be an option for Audi's driver line-up, Gass added: "Possibly, yeah. He’s a well-educated racing driver, everything was professional, so that we think it’s good to have an eye on him."

Gass also said that de Vries' links to McLaren were of no concern, as they did not prevent him from travelling to Moscow to act as Rockenfeller's potential replacement.

Unchanged line-up for 2018 likely

Despite slimming down to six cars for the 2017 campaign like DTM's other manufacturers, Audi added sportscar aces Rene Rast and Loic Duval to its line-up this season.

Gass said those changes meant any further modifications to its roster for 2018 were unlikely.

"Currently I don’t," he said. "We have made some significant changes for this season and it’s not finalised yet but I could very well imagine carrying on the same way."