Police are appealing for witnesses after a car collided with a man on the A283 at Steyning.
The incident occurred in a layby shortly before 6.30pm on Wednesday 5 June.
The victim, a local man in his 60s, was hit by the car which then drove off. He is currently being treated for his injuries at Royal Sussex County Hospital in Brighton.
Police enquiries led to the arrest of two people shortly afterwards, who remain in custody at this stage.
Detectives are appealing for anyone who witnessed the incident – or anyone who has dash cam or CCTV which may have captured it – to report it online or call 101, quoting serial 1073 of 05/06.
You can also contact the independent charity Crimestoppers anonymously on 0800 555 111 or report it online.