Kimi Raikkonen has tested this year's GP3 car in Barcelona.
Reports said the 2007 world champion, friends with GP3 team owner Afa Heikkinen, was at the Spanish grand prix venue to help with the feeder series' 2014 development programme.
He told the series' official website that the car was "actually fun to drive".
But to Finland's Turun Sanomat newspaper, he joked: "It was good, but they should think about putting an engine in the car."
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