Force India joined Brawn GP in using the Mercedes engines by signing a five-year deal until 2013, having ended their previous supply contract from Ferrari. The retirement of Red Bull Racing driver David Coulthard led to the appointment of Sebastian Vettel as his replacement, who left the Scuderia Toro Rosso team after a successful previous season including winning the Italian Grand Prix. Toro Rosso, a team designed to develop new Formula One drivers, saw co-owner Gerhard Berger sell his half-stake back to Red Bull, claiming that the new regulations would "leave no room for improvement for a small team like STR", Franz Tost took over as team boss. Filling Vettel's race seat in Toro Rosso was Sébastien Buemi, who as part of the Red Bull Junior Team competed for Trust Team Arden in the GP2 Series.