Kubica says BMW Sauber must react quickly

The Pole and teammate Nick Heidfeld endured their most disappointing showing of the year at Magny-Cours and, on the back of a strong start to the season, he is adamant they cannot afford similar results in the races to come.

"We are currently far from the pace we need in order to challenge our front-running competitors and it's no secret that we need some good updates to get back to the level of competitiveness we showed in the early part of the season," Kubica said in an interview with the official Formula One website.

"The missed podium in Magny-Cours shows that we cannot rely on the others hitting trouble. Lewis's penalties probably just put one less car in front of me at the finish line."

He added: "In Magny-Cours our gap to Ferrari was the highest so far and this was emphasised by the fact that some other teams have instead closed the gap to us. It's a signal that we need to take very seriously - and one we must react quickly to."

Heidfeld told autosport.com last week that he believed improvements tried out to the F1.08 at the recent Silverstone test were enough to get BMW Sauber back to the level they need to challenge Ferrari and McLaren.

However, Kubica believes the next few races will provide a key indicator as to who has the ability to fight for the championship.

"It's not only the gap with Ferrari - we can also take it for granted that McLaren will also be there," he said. "Moreover, we have seen Toyota and Renault in better shape.

"So I think that Silverstone, and also Hockenheim, will somehow become the turning point of the season, with everybody challenging everybody else in order to find their real positioning in both the drivers' and Constructors' Championships.

"The test in Silverstone was altogether positive and I think that some good decisions were taken. Obviously, the answer will come next week."