Robert Kubica acknowledged having mixed feelings after driving a Formula One car for the first time in six years, saying the experience reminded him of what he had lost.
Former BMW Sauber and Renault driver Kubica's F1 career was cut short when he sustained life-changing arm injuries in a rallying accident in 2011.
The Pole has focused on the World Rally Championship since his motorsport comeback in 2013 but made a return to single-seater driving by testing GP3 and Formula E cars in recent months.
Kubica completed 115 laps in a 2012 specification Renault as part of a private test at the Circuit Ricardo Tormo in Valencia on Tuesday - the same track at which he completed his last test shortly before his crash.
"I would like to thank everybody for making this possible, I hope it was a good day for everyone and maybe they saw something of my old, 2010 self," he said.
"For me, it has been an important day from an emotional point of view. It has been a long time away from the paddock and I have been through difficult periods. I kept working hard and a few years ago I felt it was impossible.
"I have mixed feelings. I am proud with what I achieved today, but also it shows what I have lost.
"I don't know what the future will bring, but I know one thing - after working for more than one year to prepare for this, I ran with good pace and consistent in difficult conditions.
"It is not easy after six years, but I knew I could do the job and I can be satisfied. I appreciate the opportunity.
"Renault gave me my first F1 test in 2005, so I appreciate another test this time around."
Renault sporting director Alan Permane added: "This was a one-off event for Robert. His time with Renault was cut short so abruptly and we perceived such a nice future with him.
"The team was in Valencia testing with Sergey Sirotkin, so it was the perfect opportunity to offer Robert a day in the car and contribute in our way to his recovery."
Kubica achieved 12 podium finishes during his F1 career, including victory at the 2008 Canadian Grand Prix.