Several motorists had to take evasive action, and once he reached the Toll Rd, he overtook three motorists at more than 170km/h, and eventually two patrol cars boxed him in.
In explanation Cowley told the arresting officer - "I guess I just wanted to have some fun."
Cowley was also sentenced on two further charges - theft of $700 from his stepfather and failing to answer district court bail.
His lawyer William McNicol urged Judge Glen Marshall to impose the recommended supervision sentence and usual disqualification, as his client had already taken rehabilitative steps
That included arranging to see a psychiatrist to help him with his mental health issues, and he was also due to have a brain scan, he said.
Mr McNicol said Cowley had also engaged with Hanmer Clinic and another organisation to assist him with his workplace integration.
Judge Marshall said Cowley's driving was extremely dangerous.
If it had not been for his "significant health difficulties", age and engagement with the Community Mental Health unit, he would have had no hesitation in sending him to prison.
"It's a wonder you, and your passenger or other road users, were not killed as a result of your driving. It was incredibly dangerous," the judge said.
Judge Marshall warned Cowley that it would be prison next time if there were any repeat of the "appalling piece of driving".
Cowley was disqualified from driving for a further 18 months from June 21 to "keep him and other road users safe", and ordered to pay full reparation.