"You turned and spat at him square in the face," the judge said.
The officer's victim-impact report said the incident had placed "undue stress" on his family because he needed two hepatitis tests.
"In my view, the police are entitled to be treated with respect," Judge Weir said.
The main aggravating factor was Wade's eight pages of convictions, including 41 dishonesty offences, Judge Weir said.
He sentenced Wade to 12 months' prison for the attempted unlawful taking of the car, two months for the assault on the officer and one month for driving while disqualified.
The judge noted Wade had never held a driver's licence but continued to drive.