Heidfeld happy with BMW's progress

"Before the season started I said that we shouldn't put too much pressure on ourselves, but at the same time we needed to be sure that we were heading in the right direction and could maintain a consistent rate of improvement," said Heidfeld, who scored the team's best result of the season so far in Australia, finishing in fourth place.

"That's certainly been the case in the first three races of the season. The team collected its first points in Malaysia and in Australia we finished fourth and sixth. On both occasions we showed good race pace."

BMW took over the Sauber team last year and the German company is racing under its own name this season. The team are currently in fifth place in the standings.

Although Heidfeld admits the result in Australia boosted the team's morale, the German is refusing to get carried away.

"We will keep on working hard and making further improvements," he said. "The outstanding performance in Australia has put an even greater spring in our step.

"However, our success in terms of race results will also depend on how other teams fare in the remaining races, so I wouldn't like to commit myself."