The man was found injured at around 4.40am on Friday 21 July 2023 near where Maypole Road becomes Ford Hill, between Sturry and Broomfield.
He was taken to hospital where he remains in a serious but stable condition.
Investigating officers are working to establish how the man came by his injuries and whether any other vehicles were involved.
As part of their enquiries, police would like to speak to the driver of a small white van, who is a potential witness.
The vehicle, described as a Citroën Berlingo-type van, is believed to have been in the area shortly before the man was found injured.
Anyone with information regarding the incident, or anyone who has private CCTV or dashcam footage which might assist, is urged to call Kent Police on 01843 222289 quoting 22-1109.
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