Kimi Raikkonen got back on track a week ahead of his Formula One rivals when he completed 270km of testing in a GP3 car at Barcelona's Circuit de Catalunya on Friday.
Formula One, which ends an August shutdown at the Belgian Grand Prix next week, bans regular testing during the season but drivers can clock up as many miles as they want in cars used in other series.
Raikkonen, the 2007 world champion who is currently second in the standings for Lotus after 10 of 19 races, took part in the official GP3 test to help his friend Afa Heikkinen, who manages the Koiranen GP team.
GP3 is a rung below GP2, the recognised feeder series for Formula One, and the test was aimed at collecting data to improve the cars and allow more overtaking next season.
"I was curious to see how the car handled and it was actually fun to drive," Raikkonen told the official GP3 website (www.gp3series.com) after completing 58 laps - nearly an F1 race distance.
"The GP3/13 (car) is a very good tool for young drivers, especially when you have to learn about tyre management like we have in F1."
GP3 cars, with no power steering and engines producing a mere 400bhp, are a long way from Formula One but the track time will have helped the Finn limber up for Spa-Francorchamps.
Raikkonen, winner of the season-opener in Australia and now 38 points behind Red Bull's triple champion Sebastian Vettel, will be one of the favourites in Belgium after winning there four times previously.
"For me it is the greatest racing circuit in the world. It is my favourite place. I have liked the place since my first ever visit there in 2000 with Formula Renault," he said in a Lotus preview for the race.
"I don't know how it will suit our car this year. Last year we were not very strong there. I think we know the reasons and for sure our car is better this year," added the Finn, who will be chasing his 28th successive points finish.