Last month's announcement that Mercedes is to quit the DTM in favour of Formula E has left the German tin-top series facing an uncertain future, with only Audi and BMW committed for 2019 and beyond.

While series chief Gerhard Berger expressed confidence that the championship can withstand the blow of Mercedes leaving, Audi boss Dieter Gass admitted he found the idea of a two-marque DTM "difficult to imagine" and stressed the importance of attracting another manufacturer.

One avenue the DTM has explored in recent years has been a push towards a four-cylinder turbocharged engine, originally set to come into force for 2017 but later pushed back to 2019, in order to attract one of Super GT's manufacturers, Honda, Lexus (Toyota) and Nissan.

Mercedes' exit means making DTM's rules more similar to Super GT has taken on fresh importance, according to Marquardt, but the BMW boss also stressed that the series needs a 'Plan B' - and that this could involve more radical changes.

"The target has to be with maximum force now, to really get potential [newcomers] attracted even more," said Marquardt. "For sure there will have to be some incentives, we have to work on that.

"Already there are three manufacturers in Super GT that run pretty similar regulations that are pretty close to what we have. So getting those closer [is Plan A], and then see what can be a Plan B."

Asked if Mercedes' pull-out would lead to a renewed push to harmonise DTM regulations with those of Super GT, Marquardt added: "That’s what we have to figure out now in the discussions with everybody involved, and then forge together, like BMW.

"We were included in the discussion from 2010 onwards, and we joined in 2012. That is what we need to do, reach out now to everybody potential and see what would be attractive. And in that respect, the DTM probably has to adjust.

"So far the three of us have been in our world. Now the situation has changed for sure and we have to see what is needed – what the good things in DTM to kept, and what maybe needs to be modified.

"We need to be open to anything. We need to widen the scope to see what can be discussed. Because for sure the more manufacturers we have involved, the more stability you have."

Two-tier DTM?

Marquardt raised the prospect of the DTM adopting parallel rulesets in order to accommodate a new manufacturer, recalling the period when Alfa Romeo and Opel both ran four-wheel drive cars against rear-wheel drive Mercedes in the 1990s.

"For sure there need to be changes, otherwise I wouldn’t see how you attract somebody," he continued. "If you are an outsider, the hurdle is very high.

"You just have to see overall the picture, maybe even allow other concepts [to race], and see how they can be matched together. The Japanese are running with the four-cylinder turbo [engine] already, we are running the eight-cylinder.

"But [it's possible] to make an effort and to have those cars run together for a period of time, like in the past, when Alfa Romeo ran a four-wheel drive car and there were different concepts with Opel [whose Calibra was only loosely based on a road car]."

He concluded: "We really owe it to the fans and the supporters of the series to make the best efforts, put our own brand egos a bit to the side and push towards [what is best for] the series’ future."