The teen also started by claiming "wrongly" that he had fallen asleep, the judge said.
Reading from the summary of facts, Judge Turner revealed the details of the crash for the first time.
The teen was driving back from Invercargill to Dunedin when he started tailgating another car.
In a passing lane the two cars began overtaking cars in tandem.
At the end of the passing lane the teen remained behind the first car and crossed the centre line four times in an attempt to pass. It was always busy.
On his fifth attempt, 1km south of Waihola, with his vehicle halfway into the other lane, an oncoming car swerved to avoid a head-on collision.
The following car was unable to get out of the way.
The resulting crash killed two mothers and injured two others in a family group heading from Dunedin to Queenstown in a convoy.
The victim impact statements made for sad reading, Judge Turner said.
The teen's offending was too serious, the risk he posed to the community too high and the consequences in Youth Court were inadequate for the matter, the judge said.
The teen will be sentenced on August 18.
