He braked heavily and skidded about 50m, before colliding with the rear of a 74-year-old woman's vehicle, shunting it off the road.
The woman, who had just pulled out of her driveway and was not wearing a seatbelt, received heavy bruising to her face and rib cage in the smash.
She was taken to Hawke's Bay Hospital overnight, and spent several weeks recovering at her home.
It is understood the officer paid $89,000 for the slick black 1967 Camaro, which was written off in the crash. He'd bought it just three weeks beforehand.
Greville had stated he was "very remorseful" and that he had been "showing off" at the time, Mr Coker said.
He had also provided the victim with a vehicle while insurance arrangements were being made.
An internal police investigation was conducted after the incident.
His lawyer, Jonathan Krebs, said his client had "an exemplary record, from a distinguished career," despite only being in his 30s.
A police spokeswoman said Greville was still working for the force in an administrative role and he was not allowed to drive a police car.
She could not comment further as Greville was currently the subject of an employment investigation.
