Reliability remains a concern for BMW

Although Nick Heidfeld qualified third and finished fourth in the season-opening Australian Grand Prix, gearbox problems for Robert Kubica in that race and in testing last week have highlighted the team's area of weakness.

"We are obviously working more on the reliability side rather than performance side at the moment," Theissen said. "But we are sorting out all the individual issues one after another and I hope we are at the end of the tunnel now - or at least seeing the light there."

Theissen acknowledged that the strong start to the season, which has seen BMW Sauber emerge as Ferrari and McLaren's closest challengers, has made it difficult for his team to keep expectations in check.

"There is an inherent process which means that you definitely cannot develop as quick as expectations rise, because as soon as you achieve something then the next step is expected the day after," he said.

"We will only be happy when we win races, that is the clear target. We just have to understand that we are not there yet, so we have to push very hard to get there.

"Everybody in the team recognises the progress we make. We smell the chance to get to the top and that makes life easier because everybody is highly motivated. And I am sure when the chance materializes, we will be there."

Although BMW Sauber were criticised by McLaren for their tactic of running Heidfeld on a low fuel load and with soft tyres for the start in Australia, Theissen has confirmed that the team will continue to split their strategies between their drivers.

The team remain concerned that new safety car rules introduced this year, which sees the pitlane closed until the cars are all in formation behind it, will compromise one of their drivers if they both have to pit at the same time.

"If you get stuck with two cars behind the safety car then you have the biggest chances, but also the bigger risk of a problem. So we try to balance that.

"For the moment we still think it is necessarily the better approach, but it may change during the season when we see how they handle things with safety cars. Certainly it depends a lot on the safety car side of things."