Nick Heidfeld.

THE ASSOCIATED PRESS

STUTTGART, Germany -- Mercedes GP says it has signed Nick Heidfeld as test and substitute driver for this year's Formula One season.

The 32-year-old German driver has competed in 167 F1 races, driving for Prost, Sauber, Jordan, Williams and BMW-Sauber until last season.

He was a test driver for McLaren-Mercedes in 1998 and 1999. Heidfeld joins an all-German team, with race drivers Michael Schumacher and Nico Rosberg. Schumacher, a seven-time champion, has come out of retirement to return to the sport.