She was airlifted to Southampton General Hospital with serious head injuries but died there at 10.10pm the same day. Sussex Road Policing officers were called to the circuit and have been investigating the crash on behalf of HM Coroner for West Sussex but there is no evidence of any other vehicle being involved.
An inquest will be opened in due course.
The event was being held under the auspices of the Motor Sports Association.
Inspector Phil Nicholas said; "This appears to have been a tragic crash during a regular time trial event and our thoughts go to the victim's family, who were with her when she died."