Heidfeld concerned about tyre graining

The BMW-Sauber driver said, however, that he had enjoyed a positive day after finishing as fifth quickest in the afternoon.

"For us the sessions went well," he said. "We had no technical problems and got all the work done. But it is very difficult to get the tyres to work properly. Graining is an issue.

"As far as I could see, other drivers have the same problem. I think the order between the top teams remains the same here. Compared to last year's F1.06, this year's car obviously performs better on high downforce circuits like Monaco or Budapest."

Teammate Robert Kubica, celebrating a year since making his Grand Prix debut this weekend, topped the times in the morning, but had to settle for 10th place in the afternoon.

"The day was quite good," Kubica said. "We did a lot of laps to see how the tyres performed. Here in Hungary we use the softest tyre compound of the season, just like in Monaco. Therefore, we completed a lot of long runs to see how the soft tyres behave over the distance.

"We now have a lot of data that we are going to analyse for tomorrow. So far so good. The track conditions were not ideal today. Off the line it is quite dirty, but this situation is the same for everybody."