A drink driver who caused a fatal crash and tried to claim his dead mate had been behind the wheel has finally confessed.

Tyler Croll-Davis, 24, had been drinking and socializing at his Rakaia Gorge home in rural Mid Canterbury on September 1 last year with his friend David Muir when he took the fateful decision to drive.

They were heading east towards Ashburton on the State Highway 77/Methven Highway at about 1am in light rain when Croll-Davis lost control.

The Toyota Corona slid sideways and left the road, the court heard.

The left-hand side of the car smashed into a concrete fencepost that was supported by a large tree stump.

"The impact of that collision resulted in the immediate death of the passenger Mr Muir," the police summary of facts says.

Croll-Davis crawled out of the wreck and walked to a nearby farmhouse "where he sought medical assistance for himself".

When police caught up with him, he denied being the driver.

The farm worker said Muir, 21, was driving and that he had been the front-seat passenger and that there had been "a number of other people" in the car who he did not know.

But today at Christchurch District Court, Croll-Davis pleaded guilty to a charge of driving with excess alcohol causing death. The charge carries a maximum penalty of 10 years' imprisonment.

He also admitted three charges of driving while disqualified.

Judge Jane Farish remanded him in custody to be sentenced on December 13.