Aug.10 (GMM) The development curve of the BMW-Sauber team has plateaued recently, founder and consultant Peter Sauber admits.

The 64-year-old, who sold to the German carmaker BMW ahead of the 2006 season, said the Hinwil based team's uncompetitive showing in Hungary last Sunday was the result of a number of complex factors including tyre performance.

Clearly the third force in F1 in 2008, BMW-Sauber has recently faced an increasing challenge from the likes of Toyota, Red Bull and Renault.

Peter Sauber, referring more generally about the team's performance at recent races, wrote in the Swiss newspaper Blick: "It has not escaped me that we have made less progress than the teams around us.

"For us, the development curve at the beginning of the season was particularly steep. Now, it has flattened a little," the Swiss added.