The news was confirmed yesterday by Guernsey Police, who also said that officers in Alderney are working on establishing the cause of the incident at Fort Clonque.
The 66-year-old man, who has not yet been named, is understood to have been the only person in the car at the time of the accident on Wednesday evening.
No other vehicles were involved.
While the police inquiry is ongoing, residents in the Fort Clonque area have been warned there will be an increased police presence.
Members of the public are asked to avoid this area while the investigation is underway.
Anyone who can offer information relevant to the enquiry should contact Alderney’s police officers, said the Guernsey Police spokesperson.
“Following a single car RTC at Fort Clonque in Alderney, a 62-year-old male has sadly died,” they explained.
“Emergency services were called to the area at about 6.40pm yesterday. Enquiries are ongoing so Alderney residents will see an increased police presence in the area.