BMW Sauber has not decided whether to reintroduce its Kinetic Energy Recovery System at the British Grand Prix next weekend.

Paradoxically, the German squad was one of the only to vote to keep the controversial technology in the sport in 2010, while at the very same time not using KERS in Turkey last weekend.

BMW also ran without KERS at Monaco and Barcelona, having opted instead to focus on aerodynamic improvements.

Team boss Mario Theissen did not want to say whether the F1.09's performance, aided by a double diffuser for the first time, would have been additionally boosted with KERS at Istanbul.

"That is difficult to say," he told Germany's Auto Motor und Sport. "We know what we would have gained on the straights, but naturally we cannot quantify how the Friday tests (of the KERS system) would have gone."

Before the double diffuser was added at Istanbul, it emerged from Hinwil-based BMW Sauber that a KERS modified for the heavily revised aerodynamic configuration of the car since Spain was now ready to race.

But a decision for Silverstone has not yet been taken, Theissen said, revealing that the next substantial update for the car is scheduled for the following race, at the Nurburgring.