Sebastien Buemi is not ruling out a return to the Formula 1 grid.
Since losing his Toro Rosso seat, the 28-year-old Swiss has become a top sports car and Formula E driver.
Yet Auto Motor und Sport reports that he was back at the wheel of a Red Bull F1 car last week to help Pirelli test tyres at Paul Ricard.
There are rumours that Renault advisor Alain Prost is pushing hard for the works Renault team to consider Buemi for the future.
"I don't know if Alain wants me back in Formula 1 -- he needs me in Formula E," Buemi said.
The timing of the Buemi rumour is notable in that Renault are believed to be considering dumping the struggling Jolyon Palmer within this season.
Another potential contender is Robert Kubica, with the Pole stepping up his F1 testing this week with another run in the 2012 car at Paul Ricard.
The next rumour is that the Pole could then get an outing in Renault's 2017 car at the post-Hungarian Grand Prix test.
"I have not yet driven a current F1 car," Kubica told France's L'Equipe.
"I could not be ready for Silverstone as it would take me two days of tests in a current car. That would accelerate my chances 1,000%."
Renault boss Cyril Abiteboul said that it is "too early to say"if Kubica will be with the team in Budapest.
