DTM had looked to switch to Super GT-style two-litre, four-cylinder, turbocharged engines from 2017 as part of a joint agreement to move towards ‘Class One’ regulations.

However, the move was thought to have been blocked by Mercedes on cost grounds and the German touring car series was forced to retain its traditional four-litre V8s.

Now that Mercedes has decided to exit DTM to switch to Formula E, Ullrich believes the German touring car series is on course to adapt Super GT engines from 2019.

“With the common monocoque, with the common parts on the car that are identical in Japan and in Germany, we have from year to year done more and more,” Ullrich, who represented Audi during the initial set of meetings between two championships, told Motorsport.com.

“The separation of the last two years was mainly the engine, but this was only because one of the German manufacturers [Mercedes] didn’t want to move to four-cylinders - because in general we wanted to go together with the Japanese people.

“It was just because one in Germany didn’t want it, so we continued with the V8, and now they are leaving. So it’s not so nice, but that is what happened.

"Now we all prepared that in ‘19 we will have four-cylinder engines and [the two championships] will be very, very close.”

Ullrich added that Audi is at an advanced stage in the development of its 2019 engine, with the motor already running in the dyno.

“We have a four-cylinder engine running since about more than half a year,” he said. “And we are working on the development of the engine. BMW as well. So I think in ‘19 engine-wise it will be quite identical.”

DTM future safe

Ullrich shrugged off suggestions that DTM’s future is under threat amid Mercedes’ impending withdrawal from the championship at the end of 2018 season, as he’s confident that other manufacturers will take its place.

“We think there won't be problem as other manufacturers will be interested,” Ullrich added. "And as well here it helps if you have a rulebook together with a championship like this, like the GT500.

“Maybe somebody that comes in new and wants to come in both championships, it makes it much more efficient.”

Interview by Kunihiko Akai