The collision happened just after 9.15pm on the B2089 Udimore Road.
The man, from Broad Oak, was taken to the Conquest Hospital in Hastings with serious injuries. His condition is described as critical, but stable.
The driver of the Mercedes, a 39-year-old man from Eastbourne, was uninjured.
Police are appealing for witnesses to contact 0845 60 70 999 quoting Operation Broomfield.