BMW Sauber F1 boss Mario Theissen is expecting to see 'his' team make progress this weekend at the German Grand Prix, thanks to a number of mechanical improvements and a modified double-diffuser.

BMW had been hoping to launch a championship challenge this year, but they have been way off the pace and to date Robert Kubica and Nick Heidfeld have both struggled with the F1.09, which on the whole has been woefully uncompetitive.

Indeed in contrast to 2008 - when they were right at the front of the pack and regularly challenging for podiums - this season they have only notched up eight points, way off the current pace setters, Brawn GP and Red Bull Racing - and a tally that puts them ahead of only Scuderia Toro Rosso and Force India in the Constructors' Championship.

Speaking in the countdown to the ninth round, Theissen added that while 2009 has, of course, been a major disappointment, he is hopeful they can recover.

"Going into the German Grand Prix, we cannot be happy with the season so far. After three successful years, this recent period has been the first set-back for our team, but it is one we will overcome," he vowed. "After all, this is the same team in Munich and Hinwil that has delivered continuous improvements since the team was founded.

"It is certainly not easy to make up lost ground without the chance to do any testing, but that is what we're aiming to do.

"We are bringing a series of mechanical improvements to the Eifel mountains, as well as a further developed version of our double-decker diffuser.

"We are all absolutely determined to start moving forwards again and I expect us to experience an upturn in form."

Willy Rampf, BMW's head of engineering, meanwhile concurs that they need to improve, especially after another tough race last time out, when Kubica and Heidfeld finished a lowly 13th and 15th at the British GP.

"After our disappointing performance at Silverstone we have to turn things around at the Nürburgring," Rampf continued. "That's something we owe our many fans who always come to the race here.

"We will be bringing a modified version of our double-decker diffuser to the Nürburgring, and we have also made improvements on the mechanical side.

"Much though will doubtless depend on how successful we are at getting the Bridgestone tyres to work with our car."