Jun.25 (GMM) McLaren chief executive Martin Whitmarsh has refused to rule out speculation that the Mercedes powered team is intending to attack the 2009 world championship with two distinct car designs.

It is already clear that the voluntary advent of KERS technology next year will result in significant weight gains for F1 cars.

"The simple fact is you only need to be 12 kilograms overweight, at which point KERS becomes irrelevant anyway and you take it off," Force India technical boss Mike Gascoyne told GPWeek.

Whitmarsh said considerations of ride-height, wheelbase and centre of gravity are also important.

"I think the challenge to the engineers is to develop a KERS system that can be run at every circuit and give a lap time advantage, but it isn't easy," he said.

Whitmarsh would only say that teams "are having to consider a whole range of options", but rumours suggest that designing two cars - perhaps with different wheelbases - is among them.

He explained: "We're thinking about lots of different things, but we're working hard to have the best solutions for every circuit.

"As you would imagine, just as any F1 team, (McLaren) isn't going to show its hand on what it is doing, but inevitably you've got to try and cover all the bases."

Gascoyne, meanwhile, dismissed suggestions that KERS can immediately give formula one the right to claim it is a 'green' sport.

"We'll be throwing batteries away after each race and all that sort of thing -- is it particularly green? Well, no," he admitted.