A male driver, 56, of a black Mazda 3 died when his car crashed into a tree at Otford on Saturday, July 4.
Emergency services were called at 7.30am to Lady Wakehurst Drive, a crime scene has been set up and police are preparing a report for the NSW Coroner.
There were no passengers, but the crash was witnessed by a young female cyclist. She was "shaken" but not injured, police said.
The road was closed in both directions for several hours, with diversions for southbound along Sir Bertram Stevens Drive and McKell Avenue and for northbound traffic along Lawrence Hargrave Drive and the Princes Highway.
Anyone with information about the crash should contact Crime Stoppers on 1800 333 000