In 2000 Schumacher joined the Williams Formula 1 team. Tost followed him, working for Williams' engine supplier BMW as Track Operations Manager until 1 January 2006, when the new Scuderia Toro Rosso team hired him as Team Principal.
Following the 2007 European Grand Prix, at the Nürburgring in Germany, it was alleged that Tost assaulted driver Scott Speed after the first turn confusion caused by rain. After Tost later denied the incident, Speed went to the press describing the acrimonious situation at the team, stating that "after coming out and denying this stuff, it's just another very dishonest thing that Franz and Gerhard have said in the media to damage me and Tonio". Scott also stated that he doesn't want to race for Tost and Berger again.