Heidfeld: Sepang no better for KERS

On paper, the Sepang track's long straights should help the four teams already using KERS, but Heidfeld - who is the only one of the two BMW drivers running the device - thinks it will only really help at the start.

"Here we have one of the longest straights before Turn 1 so it should be a better help on the start," he said. "The fact that we have longer straights here doesn't make a big impact to the difference in laptime and the difference in KERS or not.

"The difference from Melbourne to here is pretty small - smaller than I would have hoped for. I thought we would come to this circuit with long straights and KERS would be a huge benefit, but it's not much different to Melbourne."

He does not think that KERS has had a great impact on performance so far, and is not sure if he will use it again at Sepang.

"The fact that I use it and Robert (Kubica) doesn't means that there is no huge difference," said Heidfeld.

"I am lighter than Robert which pushes it over the edge for me to run and him not to run, or at least that's what we think after analysing the data we have. We're still learning about it and that was the very first weekend to have it on a race weekend and we are still in the position of finding if we run it here or not."

The German reckons the main benefit of KERS at present is as an aid for overtaking and defending.

"In the race, as was mentioned by some other people not having KERS, it made it very difficult for the other guys to overtake," said Heidfeld.

"I had a car that was heavily damaged and pretty slow, and had a couple of cars behind me that were clearly quicker, but whenever they had a clearly better corner exit and could have been in a position to overtake, I boosted and they couldn't. That was the biggest difference. Unfortunately that happened when I was down in 12th place."