He also faces sentencing on a range of other charges, including burglary, theft, unlawfully taking a motor vehicle, unlawfully getting into a motor vehicle, and intentionally damaging sprinklers at Hawke's Bay Prison.
The summary, presented by Crown prosecutor Fiona Cleary, said the robbery victim, a tradesman, was asleep in his Ford vehicle, about 4.20am, in a gravelled parking area off Munro St, Napier, otherwise known as the railways land.
Tupara and his associates were passing through the area when they noticed the vehicle and decided to steal it, but had to modify their plan after finding a person asleep inside.
Returning to the vehicle, Tupara opened the driver's door, telling the man, "you're in my car" and ordering him to get out.
The man refused and pleaded to be left in peace, but Tupara swung the sock full of rocks and which hit the man twice in the face.
Tupara also swung his body into the vehicle and kicked the man, whose head whipped back into the passengers door which he opened before falling to the ground as he was hauled out of the vehicle.
The robbers fled in the Ford, parking briefly on Marine Parade to discard most of their victim's power tools to give them more room in the vehicle.
About 12.50pm that day, the four stopped at BP Stortford Lodge where Tupara told one of his associates to pour the petrol, and drove off at speed without paying for the $15 worth that had been pumped.
One of the others with Tupara at the time has appeared in the Youth Court.