The German had been called up by the team to take part in a trial as they bid to find someone to fill in for the injured Robert Kubica.And Heidfeld may have guaranteed his return to a F1 race-seat with his 1:20.361, which he clocked in the final hour of testing using the softer option Pirelli tyres.
Fernando Alonso had to settle for second place after leading the charge for the better part of the day. The Ferrari driver was 0.132s adrift of Heidfeld's best, having his set his time early in the morning when he was conducting qualifying style runs.
Michael Schumacher came home in third place with a 1:21.054. And although his time was seven-tenths slower than his P1 time from Friday, the Mercedes GP driver's lap times were a lot more consistent on his final day of testing for the week.
Lewis Hamilton put his McLaren MP4-26 up into fourth place, however, he managed just 36 laps. According to reports, it was a shortage of parts that kept the 2008 World Champ stuck in his garage for the better part of the day.
Kamui Kobayashi was next in line, the final driver to get within a second of Heidfeld's P1 time. However, it was a stop-start day for the Sauber driver as he brought out the red flags on two occasions, both due to problems with his C30.
Sebastian Vettel spent his day concentrating on short-distance runs, finishing in seventh place ahead of Sebastien Buemi.
"The team has done a good job moving on with the development of the car since I last drove it in Valencia," said Toro Rosso's Swiss driver.
"It is definitely better, although at the moment there is no point in talking about its performance level, as we are still working mainly on understanding everything about it."
Team Lotus' Heikki Kovalainen was next in line while Williams once again struggled with their KERS unit with Rubens Barrichello down in ninth place ahead of Paul di Resta, who had a late spin after earlier suffering with brake problems, and Virgin Racing rookie Jerome D'Ambrosio.
Times
01. Nick Heidfeld Lotus Renault 1:20.361 86 laps
02. Fernando Alonso Ferrari 1:20.493 + 0.132 131 laps
03. Michael Schumacher Mercedes 1:21.054 + 0.693 114 laps
04. Lewis Hamilton McLaren-Mercedes 1:21.099 + 0.738 36 laps
05. Kamui Kobayashi Sauber-Ferrari 1:21.242 + 0.881 84 laps
06. Sebastian Vettel Red Bull-Renault 1:21.574 + 1.213 98 laps
07. Sebastien Buemi Toro Rosso-Ferrari 1:21.681 + 1.320 92 laps
08. Heikki Kovalainen Team Lotus 1:21.711 + 1.350 61 laps
09. Rubens Barrichello Williams-Cosworth 1:22.227 + 1.866 99 laps
10. Paul di Resta Force India-Mercedes 1:22.945 + 2.584 64 laps
11. Jerome D'Ambrosio Virgin-Cosworth 1:25.471 + 5.110 72 laps
Source: Planet-F1
