An explosion alerted a Dandenong man to a burning car in nearby parkland.
He went outside his Moomba Parade home to investigate after hearing the loud sound about 5.30am on Saturday 9 June.
He saw the blue 2005 Mazda 3 sedan alight and called triple-zero.
CFA crews attended and extinguished the suspicious blaze.
Greater Dandenong CIU Detective Senior Constable Tony Lavars said the car was stolen from a Cranbourne West home between Wednesday 6 and Thursday 7 June.
Anyone with information should call Greater Dandenong CIU on 9767 7444 or Crime Stoppers on 1800 333 000.