For the 2006 season , BMW Sauber signed Nick Heidfeld from Williams to be the lead driver , while World Champion Jacques Villeneuve had his existing two-year contract with Sauber honoured .
For the 2006 season , BMW Sauber signed Nick Heidfeld from Williams to be the lead driver , while 1997 World Champion Jacques Villeneuve had his existing two-year contract with Sauber honoured .