The road was closed earlier today (Friday January 23) after it was blocked in both directions between the Church Lane junction and the B2114 Brighton Road junction.
The incident was reported at 11.20am, and a grey Ford Focus was found in a field near Truckers Ghyll.
Police believe the car collided with a tree and left the road but were unable to confirm when.
The man driving the car died in the incident, police said.
Sergeant Mark Baker, of the Sussex road policing unit, said: “It is thought possible the collision, involving just this one vehicle, may have occurred late last night or in the early hours of today.
“Anyone who saw what happened or who may have other information is asked to email [email protected] or phone 101, quoting Operation Bexley.”
The road closure, between Handcross and The Wheatsheaf Pub at Ashfold Crossways, in Lower Beeding, is expected to be in force until at least 3pm.