Feb.7 (GMM) Nick Heidfeld has backed teammate Robert Kubica's claim this week that BMW-Sauber is making progress with the performance of its new car for 2008, the F1.08.

Shortly after the car made its test debut last month, 30-year-old Heidfeld expressed concern that the handling was not as good as its predecessor, the F1.07, which powered the team to second in the 2007 constructors' title.

But after the recent Barcelona test, the German racer on Wednesday gave a more promising review about the 2008 car to the BMW-Sauber website.

"We can steer the car much more accurately now," he said, although he is still reluctant to say how BMW shapes up against its 2008 rivals.

"We don't know the car well enough yet," Heidfeld continued. "There is still so much to do before the season starts in Melbourne, so it is impossible to make any predictions."

Team boss Mario Theissen suggests that the deficit to the top teams, Ferrari and McLaren, is about five tenths per lap.

"That's a major challenge (to close). But we are, above all, ambitious," he said.