Winward driver Auer completed 66 laps of the Hockenheim circuit in Germany in a test session on Thursday, where he was joined by five other GT3 and 16 LMP3 cars.
With temperatures hovering around 20C, the Austrian set a best lap of 1m37.911s in his Winward Mercedes, putting him comfortably clear of all GT3 entrants that were simultaneously testing at the venue.
Auer had previously taken pole position in last year’s Hockenheim DTM round with a time of 1m36.479s, although a difference in conditions means a direct comparison is not possible.
The 28-year-old was also driving on Pirelli tyres in the test compared to the Michelin rubber he used to convert pole position into a clear victory in the penultimate race of the 2022 DTM season.
The private test was crucial for Auer as he had missed the official DTM running at Spielberg last month, where David Schumacher was the only driver representing his Winward team.
However, while Auer did miss out on two days of valuable running at Spielberg, he was on track at Hockenheim as soon as the session began at 9:00am - and then was among the first to set serious lap times.
His opening stint lasted 12 laps, which was an encouraging sign for his recovery.
Auer had to undergo surgery in the US after breaking his vertebrae during practice for the opening round of the IMSA SportsCar Championship at Daytona Speedway in January.
The crash forced him to miss the remainder of the weekend as well as February’s Bathurst 12 Hour, where he was due to compete for Craft Bamboo as part of an all-Pro Mercedes line-up.
Auer has since been undergoing rehabilitation in Austria and reported during the official DTM test at Spielberg - which he watched from the sidelines - that he was no longer in pain.
Winward team boss Christian Hohenadel has since been keen on giving him as much track mileage as possible on Pirelli tyres, with the Italian brand taking over from Michelin as DTM’s official supplier this year.
Auer has spent the last few years primarily competing in the DTM and hence on Michelin tyres, although he did gain some knowledge of Pirelli rubber when he competed in five rounds of GT World Challenge Europe Endurance Cup last year.
The 2023 DTM season will begin at Oschersleben on May 27-28.
