His 2006 GP2 championship happened at the same time there was a vacancy at McLaren . Juan Pablo Montoya left Formula on to race in NASCAR , and Kimi RÃ ikkÃ nen left to join Ferrari . His 2006 GP2 championship coincided with a vacancy at McLaren following the departure of Juan Pablo Montoya to NASCAR and Kimi RÃ ikkÃ nen to Ferrari .