A black Peugeot was torched outside a Dandenong North home.
A Deakin Crescent neighbour noticed the flaming car parked on the street about 12.30am on Thursday 22 September.
Greater Dandenong CIU Detective Senior Constable Bree Jarvis said the fire caused substantial damage to the vehicle, which was towed.
She said there was no evidence of an accelerant and the investigation was ongoing.
Call Crime Stoppers on 1800 333 000 with any information.
