About 5.30am last Friday, the boy's father, Stuart Large, had left his son Noel, 4, in the car with the engine running as he ran inside a Caltex service station in Clyde Road, Berwick. When he came out about 20 seconds later, he saw his maroon Ford Falcon being driven away with his son inside it.

Mr Large raised the alarm and 20 minutes later police located the car at Coles car park in Clyde Road.

"When I saw my car being driven away, I just thought about my kid. I couldn't get my legs to work. I stumbled back into the service station and had them call the police."

When Mr Large was reunited with his son, he wanted to hug him forever, he said.

"This was the most horrific, gut-wrenching thing in my life. It's a parent's worst nightmare.

"It doesn't matter what time of the day it is, anything can happen to your child in a matter of seconds," he said.

Police believe the thief phoned 000 to tell them where he had dumped the car.

Acting Sergeant Colin Clarke, of Narre Warren police, said it suggested that the offender had compassion.

"I urge the offender to hand himself in. We're looking at charges for theft of a car and not kidnapping."

Detective Senior Constable Peter Lockman, of the Narre Warren crime investigation unit, said police wanted to speak to a driver in a silver Porsche who tried to chase after the car thief.

The offender was last seen jumping into a red four-door Ford laser with possibly four people inside. He is about 28 to 30, with short black hair.

Information to the Narre Warren CIU on 97053114 or Crime Stoppers on 1800333000.