The 33-year-old driver from Lewes and his passenger, who Sussex Police say was also from the area, were both pronounced dead at the scene of the collision just before 11pm.
Sergeant Richard Hornsey said, “Tragically this collision has resulted in the loss of two lives.
“We are trying to establish the circumstances of how the car came to leave the road and would like to hear from anyone who may have witnessed the collision.”
A police spokesperson said the vehicle was travelling northwards, though the two men have not been formally identified.
Anyone with information is asked to email [email protected] or call 101 quoting Operation Annescroft.