Matthew Cobden was asked whether Alexander Worth, 13, could have a picture with the high-performance car in August 2016.
Winchester Crown Court heard the 39-year-old offered to give the youngster a ride instead – and they drove along a quiet farm road in Hampshire with good weather conditions and visibility.
Thomas Wilkins, prosecuting, said: “Alexander died when the defendant’s car drove off the right-hand side into a long fence post which launched the vehicle into the air, flipping it and turning it through 270 degrees.
“No other vehicle was involved and the prosecution say that the fatal incident was caused by a simple driver error – in other words, Mr Cobden’s driving fell below that required of a careful and competent driver.”
Cobden is accused of causing death by careless driving but denies the charge.
According to Mr Wilkins, the defendant said the Ferrari “took off uncontrollably” shortly before he had put his foot on the accelerator.
The court heard Cobden said he had not experienced any difficulties with the vehicle before the crash, and “ample evidence” suggested the car had been in good working order earlier that day.
Mr Wilkins said the defendant may have failed to realise that the left-hand drive had “drifted” off the road, adding: “Another explanation is the defendant misjudged the formidable power of this iconic car, over-accelerated and lost control.”
In court, the Ferrari F50 involved in the crash was described as “the nearest you can get to a Formula One car on a public road” as the model can go from 0mph to 60mph in less than four seconds.
On the morning of the crash, Mr Wilkins said the Ferrari had been taken for a photo shoot in Lincolnshire in preparation for auction.
He added that the car had also been driven by motoring journalist Richard Meaden, who described it as a “fabulous example of the Ferrari F50”.
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The prosecutor told the court: “(Cobden’s) defence is that nothing he did caused the crash, rather it was due to some latent defect with the vehicle which caused it, without warning, to roar off and he was unable to control it or stop it in time.”
The trial continues.