After a confrontation with a woman, the pair left in her Holden about 5.50am, travelling north at speed.
Witnesses later told police that Savigny had ploughed through road cones in a 30km/h zone in State Highway 1, overtaking other motorists and causing them to take evasive action.
They were captured on CCTV refuelling at a service station in Palmerston.
Savigny subsequently overtook three vehicles, crossing double yellow lines in a 50km/h zone in the township.
At 6.56am, police spotted the defendant passing through Alma, weaving within his lane and crossing the centre line.
Police pursued but Savigny increased his speed to 130km/h.
When officers lost sight of the car they abandoned the chase.
Just minutes later, however, they found the vehicle - split into two pieces at the intersection of Severn St and Wansbeck St in Oamaru.
A serious crash investigation found Savigny hit speeds of 150km/h when he lost control, skidding over a footpath, clattering into a 50km/h speed-limit sign and colliding with five trees.
Such was the force of the crash, Blair's body was thrown 15m from the crash site. He died instantly.
Savigny was hospitalised and a sample of his blood tested positive for cannabis and methamphetamine.
He said he recalled driving erratically that day, but did not remember whether he was driving at the time of the crash.
The court today heard Savigny had previously been convicted on a significant number of driving charges.
Defence counsel Anne Stevens, QC, said her client was willing to participate in restorative justice with Blair's family.
She requested a psychological report on the defendant before sentencing on December 3.
