Brian Buchanan, 22, failed to stop after striking Steven McIlquham, 15, as he crossed the road.
The schoolboy was walking home from visiting his grandparents when the crash happened.
The impact sent him flying over the top of the Volkswagen Golf.
The incident happened in Wishaw, Lanarkshire, on January 1, 2020.
Mercy crews raced to the scene but were unable to save Steven.
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His mum Amanda found out about the crash after she went to a police station to report Steven missing.
He told police: “I just panicked and drove away.”
Experts estimated he drove at 45mph on a 30mph road.
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Buchanan, of Shotts, Lanarkshire, admitted causing death by careless driving and failing to stop.
Sheriff Martin Jones deferred his sentencing until November and continued bail.
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