Ralf Schumacher says he was surprised by his struggles in DTM qualifying at Lausitz, and is not sure why he was so far off the pace.
The six-time grand prix winner will start the third round of the season from 17th on the grid, leaving him on the back row while two of his HWA Mercedes team-mates (Paul di Resta and Bruno Spengler) share the front row of the grid.
"The car behaved OK, I'm really surprised that I am that far back," Schumacher told reporters on Saturday evening. "I've struggled a bit the whole weekend on this track, but there is no main reason.
"We have to look into it, there is obviously something I am doing wrong because to be more than one second away from the front is a lot."
Schumacher added that Mercedes was unsure of what the problem could be, as Gary Paffett also struggled and could only manage ninth on the grid in the fourth HWA car.
"It's corner speed in general, entry and exit, I just seem to have less grip which is difficult to understand," said the German. "The car doesn't feel strange compared to usual. Looking at the details, even Gary had some problems today. The car is just slow and we don't know why."