Nick Heidfeld has moved tantalisingly close to securing a race drive for the 2011 season.
The prime candidate to replace injured Robert Kubica, 33-year-old German Heidfeld tested the Renault R31 at Jerez on Saturday and topped the timesheet.
Team boss Eric Boullier said he had made a "very positive" impression.
Heidfeld told F1's official website that he had started the day with the aim of doing his "best to get me a future drive", and ended up kicking off the new car's development programme.
"I think that the car was already different in the afternoon from where I'd picked it up in the morning. I think we've improved it over the course of a test session," he said.
Heidfeld's pace was also obvious, as after 15 laps he was already six tenths faster than his potential 2011 teammate Vitaly Petrov.
"Yes, I think I've done a good job," said the former Prost, Sauber, Jordan, Williams and BMW driver.
"What others interpret into that time is not up to me," he added.
Reigning world champion Sebastian Vettel admitted Heidfeld "looked pretty good" in the black and gold Lotus-sponsored car at Jerez.
"That the Renault seems pretty competitive we've already seen in Valencia," added the Red Bull driver, "and his life as a pensioner obviously can wait!"