The incident caused the car to overturn on the motorway outside Oslo on Saturday and the women are suspected of causing serious bodily injury.
A video from the scene shows the car driving on the other car several times shortly after Sian had burned a Koran at an intersection. The women, one who was driving the car and one passenger, had been at the scene of the Koran burning and then followed the Sian car.
Five people were traveling in the car at the time. One was taken to hospital but no one was seriously injured.