Robert Kubica completed 90 'trouble-free' laps in his second test for Renault as the popular Pole steps up his remarkable Formula 1 comeback bid.

Renault claimed the test at France's Paul Ricard Circuit was designed "to extensively evaluate his driving capabilities" as he recovers from the career-changing injuries sustained in 2011, and have confirmed that Kubica was untroubled in the 2012 E20 on Wednesday.

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"Physically, there are no problems," Kubica is quoted as telling French publication L'Equipe.

"My doubts about my capacities have disappeared with these two days of tests. I am no longer afraid of not being at the level but there remains a way to go."

The second outing, which Renault team boss Cyril Abiteboul admitted brings a return "to the highest level of competition" ever closer, is the clearest sign yet that they are considering rehiring the 32-year-old for 2018 with Jolyon Palmer's future unclear.

A future race return for Kubica, absent from the sport since suffering severe arm injuries in a rallying accident six years ago, would represent one of F1's most astonishing and heart-warming stories.

Kubica's first comeback drive for the team occurred at Valencia when he ran in the same 2012 car that he ran in at Paul Ricard, and he completed over 100 laps. It is understood that Kubica was immediately quicker than Sergey Sirotkin, the Renault test driver.

After that test, Kubica, a race-winner with Sauber in 2008, was adamant that he could return to F1 full-time.

Former F1 driver Robert Kubica says testing with Renault in Valencia was a great opportunity and that he is physically ready for the challenge. Former F1 driver Robert Kubica says testing with Renault in Valencia was a great opportunity and that he is physically ready for the challenge.

"I will keep working and hopefully one day I will have a chance to go forward and step-by-step maybe have [a] proper comeback," he told Sky Sports.

There have been suggestions that Kubica could be drafted in by Renault to complete a day of running in their 2017 car in the official post-race test in Hungary at the start of August.

After Nico Hulkenberg and Sirotkin ran at the Bahrain test, Renault can use either of the two days in Budapest to test an experienced F1 driver.

"I don't want to come back for nothing," Kubica added to L'Equipe. "I want to come back to the best possible level. I haven't tested a current-spec car, so I wouldn't be able to be ready for Silverstone.

"I would need a couple of days in a car, and that would boost my chances by 100 percent! Honestly, I'm doing my best to maximize my chances. But I don't know what the future holds."