In 2001, Zanardi lost both of his legs — and almost his life — in a ChampCar crash at the EuroSpeedway Lausitz, 13 laps from the end of the race.
Twenty months later, the former Williams F1 driver returned to the track to complete the 13 laps and went on to race in the European Touring Car Championship.
He also took up handcycling, winning two gold medals and one silver at the London Paralympic Games in 2012, followed by a further gold and silver at the Rio Games, four years later.
He was competing in a handcycling road race last month when he collided with a lorry during a descent.
Zanardi, 53, was airlifted to hospital in a serious condition with a “severe head injury”, and went into surgery within an hour of arriving.
A criminal investigation has been opened into the incident and the race’s organisation, to look at whether safety precautions were sufficient.
On the day of his crash, BMW announced that he was due to race in the Italian GT Championship this November. He had also announced his intention to target further medals at next year’s Paralympic Games in Tokyo.