The collision took place on the A340 near Pamber End, Tadley, at around 1.45pm on 8 November.
A blue VW Golf was driving on the A340 when it left the road and veered into a ditch.
The driver, a 17-year-old boy, was taken to Frimley Park Hospital with serious injuries.
Officers have been conducting a number of enquiries and are now turning to the public for help.
Police are looking to hear from anyone who saw a blue VW Golf driving on the A340 before the collision.
Were you in the area at the time? Perhaps you witnessed a VW Golf driving dangerously?
Anyone with information is asked to phone 101 with the reference 44200433300.