Oct.15 (GMM) BMW-Sauber will use a philosophy of evolution to attempt to close the gap to F1's two top teams in 2008, team boss Mario Theissen says.



The German, whose Hinwil based outfit established itself as clearly the third force on the grid this year, estimates the average deficit to Ferrari and McLaren at the moment as "about half a second per lap".



"I wouldn't say there is one area where we are massively behind," he added.



"This year's car is quite well balanced but we are lacking a little bit everywhere," he explained.



Theissen revealed that BMW's 2008 car, to be called the F1.08 and again raced by Nick Heidfeld and Robert Kubica, is not going to be a radical departure from its predecessor.



"It is an evolution rather than a revolution in order to find the ultimate three to five percent which is missing," he said.