BMW test driver Christian Klien dismissed claims the team are way ahead of their competitions in terms of development.

Klien, though, insists they will only know where they stand once competition gets underway in Melbourne at the end of March.

"We were the first to run the '09-spec aerodynamics, which slows you down massively," he told the official F1 website.

"As always, the winter testing lap times do not mean a great deal.

"Teams were using all sorts of different aero packages. Everyone was doing individual programs. Some were testing potential candidates for 2009, in 2008 spec cars. And KERS development has really only just begun.

"The important thing is to follow your own program and exchange as much data as possible between the three drivers.

"When it comes to this, it has definitely been a few good weeks of testing. Again, we will only know where we stand in comparison to our competitors at the start of the race season."

The Austrian also believes BMW still need to do a lot of testing before deciding whether to use KERS in the opening few races of the season, and also downplayed the supposed handicap that taller drivers will have.

"We will really have to test KERS in the new car first before we have a clearer picture," he said.

"As it is not mandatory, every team will weigh the options very carefully. How much do you gain from it? How much can you lose by reliability issues?

"There is a small advantage for lighter drivers. 10 kilos less of body weight gives you 10 kilos more to play with your weight balance. But it does not have a dramatic effect.

"As much as I myself would love to have an edge over bigger drivers, I doubt KERS will be the end of the story for them. The difference is quite marginal."