The A23 has fully reopened after a fatal crash on Saturday night, Sussex Police said.
Three men have been arrested on suspicion of causing death by dangerous driving.
Sussex Police said: “We are appealing for information following a serious collision on the A23 near Bolney on Saturday (10 August).
“Emergency services responded to report of a single-vehicle collision in the southbound carriageway at around 10.10pm.
“A 25-year-old man was treated by medical personnel at the scene but was sadly pronounced deceased a short while later.
“His next of kin have been informed.
“Three men, all aged 25 and from London, were arrested on suspicion of causing death by dangerous driving.
“The southbound carriageway has now reopened after a previous closure while services worked at the scene.
“Inquiries are under way to establish the circumstances of the collision and we ask those with dashcam footage or who witnessed the collision to contact police.
“You can contact police by emailing collision.appeal@sussex.police.uk or by calling 101, quoting Operation Promise.”