Mercedes reserve driver Nick Heidfeld has left the Formula One team to become test driver for tyre supplier Pirelli.
Heidfeld, who joined Mercedes in February as part of an all German line-up led by Michael Schumacher and Nico Rosberg, has been released from his contract, to help Pirelli prepare for their return to Formula One.
The Italian tyre company, who are returning to the grid for the first time since 1991, were appointed in June as Bridgestone's replacement for next season as the sport's sole tyre supplier on a three-year deal.
Heidfeld made his Formula One debut in 2000 for the Prost team and went on to race for Sauber, Jordan, Williams and BMW Sauber.
He developed a reputation for consistency but failed to win a race in his nine-year Formula One career.
