Before every race, Button sites on an inflatable gym ball, holding a steering wheel, shuts his eyes, and drives a lap of the circuit. He "makes all the noises too", and when he opens his eyes at the end of this visualised lap, he's usually within a second of his real lap times. (interviewed by Jackie Stewart on the ITV show before the French GP 2005.)
Update: Fernando Alonso practices on PlayStation:
The man who could be Formula One’s youngest world champion has raced this [Turkey] circuit in imaginary grands prix a hundred times, but only on his PlayStation in the living room of his Oxford home. And he has won every time.
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