Two-time DTM champion Mattias Ekstrom believes that the interest shown by Timo Glock and Robert Kubica in the series is proof that it is getting stronger.
Glock is the latest driver to choose to continue his career in the German-based series after leaving Formula 1, following the likes of Jean Alesi, Mika Hakkinen, Heinz-Harald Frentzen, Ralf Schumacher and David Coulthard.
While the ex-Marussa driver got to grips with the BMW M3 last week at Valencia, Robert Kubica was also in action with Mercedes, as he continues to recover from the injuries he sustained in a rally crash in 2011.
"All of these drivers - it doesn't matter where they come from or whatever they do - it shows DTM is getting stronger year by year," said Ekstrom.
"Timo lives close to me, and he is a hero in Germany. I think he will be a good strength for the DTM."
Ekstrom also wished Kubica well in his return to competitive motorsport.
"I really hope and wish that Robert can be healthy enough to drive in a professional series again," he added.
"I followed his career very closely for a long time, and I know his passion for rally is high like mine.
"After his accident, I think it would be great it he could come back to professional sport again."