King, 19, recently pleaded guilty to careless driving causing death, while under the influence of alcohol or drugs, and faces sentencing this month.
On November 9, Glengarry was drinking at Boston on Blair, a Wellington bar.
At about 2am, after having a number of drinks, he decided to drive back to Masterton.
A member of the public noticed Glengarry accelerating and then slowing down, while also drifting within his lane, on State Highway 2, in Upper Hutt and called police.
Police found Glengarry at the top of the Rimutaka Hill, and after smelling alcohol, breath-tested him.
His breath-alcohol test returned a result of 501 mcg of alcohol per litre of breath, over both the youth and adult limits.
Judge Tuohy said Glengarry had pleaded guilty at the earliest opportunity and had no previous convictions.
He convicted him and fined him $500, court costs of $130, and sentenced him to six months' supervision.