Police on Thursday made a plea for witnesses to the incident, which left Mr Tung hospitalised with life-threatening injuries.

It will be a year on Saturday since Mr Tung was knocked from his three-wheel electric scooter on Yarrowee Parade after it was struck from behind by a sedan.

The 33-year-old was taken to Ballarat Health Services Base Hospital with serious head injuries and fractures to his arms and legs. He was later transferred to The Alfred hospital in Melbourne.

Mr Tung was travelling south on the wrong side of Yarrowee Parade, Redan, near the intersection with Darling Street when he was struck by the car travelling in the same direction.

Torrential rain and little street light gave little visibility to the incident which happened just before 6pm on July 19 last year.

The driver of the blue VP Commodore failed to stop and no one has ever been charged.

A car believed to be linked to the incident, was found burnt out a week later off Whitehorse Road in Mt Clear.

Mr Tung lost some of his cognitive functions, including talking, remembering and problem-solving and spent several months attending specialist sessions. 

Ballarat Highway Patrol Acting Sergeant Travis Johnson said inquiries into the incident had come to a standstill and was hopeful the fresh call for public assistance would lead to a prosecution.

"From experience there is other underlying issues (for failing to stop after an accident), whether the driver may have been avoiding police or may have been alcohol or drug-affected," Acting Sergeant Johnson said.