Bruno Senna says he accepts that Renault needs a 'more prepared' driver to stand in as Robert Kubica's replacement from the start of this season.
Senna was named as Renault's first reserve driver during last week's Valencia test, but following Kubica's injuries and likely long absence, team boss Eric Boullier said he wanted a substitute with more experience.
Nick Heidfeld impressed in testing for Renault yesterday, before Senna took over today. But the team denied there was any shoot-out for the drive, with Heidfeld almost certain to take it.
After his day in the car on Sunday, Senna agreed with Boullier's decision.
"I only had one day in the car and it was good, but for preparation you need much more than that - they need a driver that's ready to do it," he said.
"It wasn't a trial. In unfortunate circumstances I was given a great opportunity to drive the car and do some work for the team. Considering that I've only been here for three weeks, it's a great shot for getting some experience with the car and the team. The team knows what they need and it's up to them what they do."
Senna said he was still pleased with his day's work and believes he made a good impression on the Renault team.
"It was brilliant," he said. "It was the second test I had in a Formula 1 car, ever. Considering I raced for a year that's quite incredible. Doing a full test day in a car makes you learn so much as a driver.
"It's been a very productive day, I think the team liked the feedback I gave them. It took me a few laps to get into the KERS and rear wing systems - it's actually quite a lot in the brain. After it becomes second nature it's more straightforward."