Officers were made aware of a collision involving a vehicle and a pedestrian on Selhurst Park Road, East Dean, shortly after 10pm on Friday, August 27.
The vehicle left the scene and despite numerous enquiries, no details of the vehicle involved are currently known, police have said.
The pedestrian, a 30-year-old man, suffered a fractured arm, ligament and soft tissues damage, cuts and bruising.
He was taken to hospital for treatment, and has since been discharged to continue his recovery at home.
Police investigating the matter are keen to speak to any witnesses, or anyone who may have captured any relevant dash cam footage from the area around that time.
They would particularly like to speak to the occupants of a vehicle who stopped to check on the pedestrian, but later drove off.
Anyone with information is asked to email [email protected], report online or call 101 quoting serial 72 of 15/09.