How a 16-year-old boy came to be driving a fake emergency truck to accident scenes around Melbourne is as bizarre as the tale itself, a court has heard.

Not content to finish school before eyeing a policing career, the boy embarked on what investigators allege is a serious chain of events that began with falsely reporting a burglary and ended with him speeding around the city's busiest roads in the emergency truck, complete with red and blue flashing lights.

Between those points, the boy allegedly defrauded an insurance company of more than $100,000, duped a hire car firm, used the online identities of his father and other adults to falsify documents, and even created a corporate accountant who existed in name only. All before his 17th birthday.

"This type of behaviour is breathtaking in its inception, execution ... I don't think we have ever seen anything like this before," a magistrate said in a Victorian children's court on Wednesday after a police prosecutor detailed the case.

The teenager, who is now 17 and working at McDonald's, was sitting in court with his mother. He cannot be identified.