After the 1955 season , Mercedes left the sport . Despite part-ownerships , and engine supplier deals in the 1990s and 2000s , it did not return as a factory team until November 2009 . However , after the 1955 season , Mercedes left the sport , and despite part-ownerships , and engine supplier deals in the 1990s and 2000s , it did not return as a factory team until November 2009 .