Heidfeld needs lift at Spa to secure F1 future

LONDON, England (CNN) -- Nick Heidfeld acknowledges he is under pressure to perform with question marks hanging over his BMW Sauber future.

The German has had a topsy-turvy year and while 41 points leaves him sixth in the championship, he has been regularly shown up by team-mate Robert Kubica.

Kubica took the team's first win in Canada in a race Heidfeld could have won, which sums up a season of frustration for the former Williams driver.

And with neither BMW driver yet confirmed for 2009, Heidfeld knows he needs to deliver in the final six races of the year.

"I put myself under pressure more than anybody else could do from the outside," the 31-year-old said.

"It's pretty clear; if one car finishes on the podium and I finish ninth, nobody needs to tell me anything.

"It's all about understanding the problems and then changing some things and trying to go quicker. I think I've made steps forward, but we will find out in the next couple of races."

Heidfeld, who is still searching for his first win in Formula One after 146 races, has only qualified ahead of Kubica once this season.

After shining in comparison with the Pole in 2007, Heidfeld has not been happy with his 2008 car and has only twice attained a top-five grid spot.

This has hurt him in the races, although in general his form in qualifying has improved after a period of mid-season soul-searching.

"I was in a similar situation earlier this year and I thought I had put that behind me," he continued.

"I was then a bit surprised to run into a similar sort of problem again in Valencia. I admit, though, my qualifying form has been erratic, up and down.

"On one hand I've had some bad luck with traffic, and secondly, I have made more mistakes than usual.

"That's obviously something I'm also working on, but I don't think that's as difficult to change as the pace problems I had earlier in the season."

At last year's Belgian Grand Prix, Heidfeld was able to finish as best of the rest behind the two Ferraris and the two McLarens.

And he is hoping for more of the wet weather that allowed him to finish second at the British Grand Prix in July.

"If I would finish there [fifth], most likely it wouldn't be a bad result but nobody knows what will happen here on Sunday," he added.

"The weather forecast isn't the best. It could rain, which I wouldn't mind because I enjoy driving in wet conditions."