Bush threatened Brown and told him he was going to tie him up so he could take the car.
When Brown resisted and began throwing things, Bush "retaliated by commencing a horrific and sustained attack against him", Justice Edwards said.
Bush struck Brown multiple times in the head with a weapon - likely a gun butt - causing "a huge hole" in the back of his head.
"Mr Brown cried out for help, but nobody came, and you did not stop," Justice Edwards said.
"There were multiple blows to his body. His legs were bound. And a cord was placed around his neck."
Bush's son came into the room to help during the attack but became upset at the extent of the violence and left the house.
Bush followed his son and tried to persuade him to come back, but he did not, Justice Edwards said.
Bush jnr has subsequently pleaded guilty to a manslaughter charge.
Leaving Brown in the bedroom, Bush then towed the Ford Fairmont away from the boarding house with the help of an associate, Daniel Tai Houia, who did not take part in the attack.
Houia was this month jailed for three years and four months for aggravated robbery.
The Ford Fairmont has never been recovered.
In his victim impact statement, Bruce Brown described his brother as "harmless".
Brown loved guitars, V8s, Triumphs, Falcons, fishing and coming home to to his mum's for a good boil up, he said.
He said his brother's murder was heartbreaking, devastating and senseless.
"It is abundantly clear that you have inflicted immeasurable pain on this family
– and all for an $800 car which did not work," Justice Edwards said to Bush.