Autopsies key to Vic car deaths mystery

Autopsy results due on Friday will help police determine what happened to a man and a woman found dead in a car in Melbourne's northwestern outskirts.

A council worker found a man in his 50s slumped in the front passenger seat of the Ford Falcon in a gravel Lover's Lane in semi-rural Plumpton outside Melbourne on Thursday morning.

He had fatal gunshot wounds to his upper body and a long-barrel firearm was beside him.

Paramedics later found the body of a woman in her 40s lying on the back seat. It's not yet clear how she died.

Detectives suspect the case is a murder-suicide.

The car was spotted a few hundred metres from farmhouses beside the isolated stretch of Taylors Road, about 12.15pm on Wednesday but Detective Senior Sergeant Stuart Bailey said it might have been there since Tuesday.

The man and woman have not been identified yet, he said.

"However, on the information we have, we believe these people are known to each other and we are not looking for a third person," he told reporters.

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