The BMW Sauber team expects to have its definitive 'double decker' diffuser in place by the Turkish Grand Prix early next month, and has said that it will reintroduce its troubled KERS technology at the same time in an effort to improve in the second half of the season.

The Munich/Hinwil operation has registered a measly six points in the opening five races of 2009 - all courtesy of the much-maligned Nick Heidfeld - and has frequently struggled to make an impact in qualifying, leading to problems on raceday. Robert Kubica's potential podium run in Melbourne remains the competitive high point of the campaign, despite Heidfeld's tactical second place in Malaysia, and the Pole - who many were tipping as a title contender after 2008 - remains scoreless through the first third of the year.

Formula One's return to Europe has at least allowed BMW - along with its rivals - to introduce the first of its planned updates, although the diffuser row means that it remains in pursuit of the likes of Brawn and Red Bull as it continues to develop the all-important 'multi-plane' diffuser. The upgrade - which included a new nose, sidepods and rear wing, plus revisions to the front wing, engine cover and diffuser - was always likely to provide a major improvement for the team, which had resisted the urge to drip-feed development parts on the car during the 'flyaway' rounds.

"Before the start of the European season, we were all curious to see the effect our extensive aerodynamic package would have in Barcelona," team boss Mario Theissen commented, "Now we know one thing for definite: the modifications have improved the F1.09. We have a taken a big step forwards, and are back in business."

Ironically, the improvements led to Heidfeld increasing his personal tally for the year with seventh place, despite Kubica having been the one to take BMW Sauber back into the final phase of qualifying on Saturday. The Pole, however, then suffered a return of the sort of luck that has plagued him this season, after his car had its tyres fitted incorrectly - costing him a shot at a better grid position - and a clutch problem that dropped him into the pack at the start of the race.

Heidfeld and Kubica also raced without the controversial KERS system - although the Pole has rarely utilised the heavy technology - preferring instead to evaluate the aero developments from a known footing before planning to reintroduce the 'power boost' at the same time as the debut of its definitive diffuser design.

"In order to be able to concentrate on the new aerodynamic package, we did without KERS in Spain," Theissen confirmed, "Our goal is to use both a modified KERS and a multi-level diffuser in Istanbul - and more development packages are in the pipeline for 2009."

While admitting that Heidfeld's two-point haul from Barcelona was hardly huge, Theissen insisted that it was the first step on the road to recovery.

"The measures are taking effect and the foundation has been laid," he claimed, "We have something we can build on - and the result has, of course, lightened the mood in the camp, as there is now a recognisable upward trend. It goes without saying that the entire team was disappointed after the Bahrain result, but this rapidly becomes a strong motivation in Munich and Hinwil. The fighting spirit and determination to get back to the top is there - and that gives me confidence for the races ahead."