A silver Jeep Cherokee reportedly fell around 30 metres from Stanmer Park onto the eastbound carriageway grass verge on Friday night (Nov 26).
It happened at around 8.40pm, following which, a section of the A27 at Falmer was closed for several hours.
Emergency services recovered three people from the car - two sustained serious but not life-threatening injuries; the third sustained minor injuries.
Following a search of the area, assisted by the National Police Air Service (NPAS) helicopter, a fourth person was located. He had also sustained minor injuries.
All four people were taken to hospital for treatment, and the vehicle was recovered and the road fully reopened as of 6am on Saturday 27 November.
Enquiries are ongoing, and anyone with any information about the incident is urged to email collision.appeal@sussex.pnn.police.uk quoting Operation Hitch.
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