Heidfeld already developing R31

The grand prix veteran drove the car for the first time on Saturday, as the team assessed his potential to fill in for the injured Robert Kubica.

And Heidfeld said afterwards that the day went so well that he was already able to give the team ideas for areas of development with the car.

"We already started today to try and improve the car, find directions, where the problems are, where the strengths are," Heidfeld told reporters at Jerez.

"I'm obviously trying to do the best job today so I can drive in the future, but I'm also just using it as a normal test and trying to develop the car.

"The car is already very different to how it was this morning, suiting my driving style a lot more. It is still not ideal - I hope there is more to come from the feeling I have - but it's a good base."

Heidfeld added that he was very happy with the job he did today, in what was effectively an audition to earn a drive with the team.

"I'm pleased with the job I did, very pleased," he said. "I don't think I could have done any better, and I didn't do any mistakes."

The German was yet to talk to the team in detail about the possibilities for the future, but he said that the uncertainty surrounding his chances has not been a distraction.

"I haven't discussed it yet," he said when asked when he expected an answer from the team. "My focus was just on today, this was what mattered.

"It doesn't help if you think about what they will tell you after the test. That takes the concentration away."

Renault reserve driver Bruno Senna will drive the R31 on Sunday, but team boss Eric Boullier has already ruled the Brazilian out of the running for Kubica's seat.