Sussex Police has issued a fresh appeal for witnesses to a serious collision on the A23 at Hickstead.
The collision, which involved a Renault Scenic and a HGV lorry, happened on Sunday (August 18).
An 18-year-old man, the front seat passenger in the car, suffered life threatening injuries and remains in a critical condition in hospital.
The driver of the car, an 18-year-old man from London, suffered minor injuries in the collision, police said, and was later arrested on suspicion of dangerous driving. He has been released on bail until September 12.
The lorry driver was unhurt, confirmed police.
A police spokesman said: "Did you see a car hit the rear of a parked lorry on the A23 at Hickstead on Sunday night (August 18 )?
"A Renault Scenic was travelling south when the collision occurred as the HGV was parked in a lay-by at 8.40pm."
PC Ian Foxton added: “We would like to hear from anyone who saw the bronze coloured Renault Scenic car travelling south on the A23 before the collision or who witnessed the collision itself. Also we would like to hear from anyone who has dash cam footage of the vehicle and the incident.”
Witnesses can report online or call 101 quoting Operation Beaufort.