Sauber went into 2005 season with sponsorship continuity. The livery had a sponsorship change with Red Bull sponsorship departing to Red Bull Racing after a nine-year alliance with Sauber. The team did not have title sponsorship due to 2004 Asian Tsunami. The front nose livery was changed to blue due to usage of Michelin Tires, previously the nose livery was white in 2001-2004 seasons.
The Sauber team was taken over by BMW for the 2006 season. A C24B variant of the car fitted with BMW's P86 V8 Formula One engine was used in early testing between the 2005 and 2006 seasons in the hands of Nick Heidfeld and Jacques Villeneuve. On November 27, 2005, Heidfeld attended a Sauber seat fitting with his former boss, Peter Sauber. On November 28-December 2, 2005, Heidfeld attended off-season testing at Barcelona in a C24B car using Michelin tyres. On December 7–17, 2005, Heidfeld and Villeneuve attended off season testing at Circuito de Jerez with the same car. Just before the launch of BMW Sauber F1.06, Heidfeld attended off-season testing with C24B car in the full white interim livery on January 10-January 13, 2006.