The body was found near Heanor Memorial Park in Derbyshire.
Derbyshire Police originally thought the man was 17-year-old Han Lan, but now believe it might be a 21-year-old man named Trung Thanh Hoang.
The inquest also heard police think he may not have died at the park but that his body was dropped off there.
Police officers are working with Vietnamese authorities to confirm his identity and to find relatives either in the UK or in Vietnam.
The inquest at  Derby Coroner's Court heard it was believed the man visited a nightclub in Birmingham on Christmas Eve before returning to an address in Derby after feeling unwell.
The cause of death is yet to be established but a toxicology report showed high levels of a number of drugs in his system.
Police are still treating his death as suspicious.
The inquest was adjourned until the end of March.
The identity of a man found dead in a car park on Christmas Day is still not clear, an inquest into his death has heard.