Shortly before 7am, police saw the defendant passing through Alma, weaving and veering into the wrong lane.
"When the offending vehicle failed to stop, the patrol unit pursued the fleeing driver from a distance," an Independent Police Conduct Authority (IPCA) decision said.
Savigny increased his speed to 130kmh.
A few minutes later the officer came across the wreckage.
The vehicle was split into two pieces at the intersection of Severn and Wansbeck Sts.
A subsequent investigation found Savigny had hit speeds of 150kmh when he lost control, skidding over a footpath, clattering into a 50kmh speed limit sign and colliding with five trees.
Neither man in the car was wearing a seat belt.
Blair died instantly, while Savigny was hospitalised.
A police investigation found the officer complied with policy at the time of the pursuit but "should have abandoned the pursuit at an earlier opportunity when they lost sight of the offending vehicle approaching the built-up area of Oamaru".
The IPCA said police had identified "several learning opportunities" for both the officer and communication staff involved to improve how they manage similar events in future.
The authority was satisfied with how the police conducted their review of the incident.
