The Italian Carabinieri said the crash happened at 8.15am on Tuesday on State Road 125 from Puntaldia towards Olbia.
He was said to be travelling 60mph at the time when the auto reportedly changed direction suddenly and collided with the bike.
Sardinian hospital John Paul II says Clooney has already been discharged, according to NBC News.
The actor was taken via ambulance to a local hospital and released later the same day.
Clooney is a Northern Kentucky native.
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George's reps told Metro.co.uk: 'George Clooney was treated and released from an Olbia hospital.
It is reported that George was then x-rayed and seen to by a doctor, before being discharged the same morning and leaving the premises in a chauffeur driven auto.
Reports note that the driver of the vehicle got out and offered assistance to the actor until ambulance arrived.
The star who lives in Sonning, Berkshire with his wife Amal Clooney and their two children, doesn't appear to be badly injured. He added that Clooney would be monitored by hospital staff as an outpatient for 20 days.
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According to some sources, Clooney was on his way to the set of Catch-22 at the time of the accident.