Police and ambulance attended, and the injured man was taken to the Royal Infirmary of Edinburgh for treatment.
Detective Sergeant Garry Mauran said: "Our enquires are at an early stage to establish the exact circumstances surrounding this incident and trace the driver and the car involved.
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"If you witnessed this take place or saw a silver car being driven erratically in the Port Seton area, please contact us.
"Anyone in the area is asked to check their dashcam or personal footage and contact us if it holds anything that may be relevant to our investigation."
Anyone with any information is asked to contact Police Scotla