Renault: Heidfeld already leading team

Heidfeld will fill in alongside Vitaly Petrov at Renault until Kubica recovers from the multiple injuries he suffered in a rally crash three weeks ago. The German had a test audition for Renault before being snapped up, and Boullier said he was very impressed by the way Heidfeld immediately took charge.

"The way he stepped into the team, he came to the factory, he had a brief introduction to the engineers and sat down with us for an hour," Boullier explained.

"When he was testing at Jerez, I was listening on the radio and the way he was talking to the engineers, he was right there [settled in the team]. I was already half-convinced that morning."

Boullier had not expected Heidfeld to step into the role so quickly and decisively.

"I was surprised about the fact that he was able to position himself so early and so easily as a team leader," said the Frenchman. "I would have understood that he could have taken some time.

"The guy, after the first run, was already clearly demanding some changes if he could stay with the team."

Boullier said that the need for a driver who could show technical leadership was a key factor in Renault's hunt for a substitute for Kubica, and that Heidfeld was always first choice.

"Because the accident happened at such an early stage of the season, we concluded very rapidly that we needed a very experienced driver - and fast, obviously - and having enough character to lead some technical decisions or to take some decisions in a firm manner with the team," said Boullier.

"When you draw up this profile, and I added if possible [that we wanted] experience with Pirelli tyres and knowledge of having raced with KERS in 2009, it was obvious that was only one ticking all the boxes, which was Nick.

"On top of this, I'd had several meetings with him last year because he'd wanted to follow very closely the situation with our 2011 second seat.

"We even discussed this with Robert actually. I was too early, he was just waking up from the coma, but Gerard [Lopez] talked with him and Robert raised two names: Nick and [Tonio] Liuzzi."

Renault also has Bruno Senna and Romain Grosjean on its books as reserve drivers, plus Fairuz Fauzy, Jan Charouz and Ho-Pin Tung within a driver development programme.

Boullier said that had Renault's need for a substitute occurred further into the year, it would have dipped into its own reserve line-up rather than recruiting an external driver.

"If it had happened later in the season, the car would have been developed. I would have gone for one of our reserve drivers," he said.

"Also, the guy would have spent six months with us [by then], he would have known everybody, he would have been aware of the procedures.

"There was too much risk to put on the shoulders of two young guys the responsibility to develop this car. That would have been stupid for me to gamble on this."