Despite being one of the surprises of the 2006 season, BMW Sauber won't make the breakthrough as Formula One winners in 2007 according to driver Nick Heidfeld.

Heidfeld, Jacques Villeneuve and Robert Kubica helped the team to finish the first season under BMW ownership in fifth place in the constructors' title race - ahead of Toyota - with Heidfeld and debutant Kubica both taking trips to the podium.

The two will reunite at the wheel of the new F1.07 for the 2007 season as Kubica competes in his first full season of F1 competition, but experienced German Heidfeld said it was too soon for the team to be expecting victories from its driver pairing.

"It is naturally our goal to win," he told Speed TV. "But we do not expect that yet even though we are going in the right direction. For 2007 we have high expectations but we also know Formula One well enough to realise that you don't become world champion in one year or two. You don't win just because you put a BMW sticker on the car.

"We are going to improve even more, but I would be content if we rose by one place to finish fourth in '07."