Rory Teiffel visited church twice on Easter Sunday before he decided to take his brother and cousins for a drive in his new car.
The devout Christian was proud of his Jeep Grand Cherokee and boasted to his family about its high performance as it had eight gears.
But just nine-and-a-half minutes after they took off, Teiffel lost control and crashed into two trees after travelling up to 246km/h.
His 26-year-old cousin Ryan Suggate died instantly.
Teiffel's 16-year-old brother Denver was rushed to hospital but could not be saved and died about six days later.
Teiffel pleaded guilty to two charges of culpable driving causing death and a summary offence of driving while beyond the alcohol limit.
He was jailed for at least five years and four months on Monday for the "tragic" crash that has left his family heartbroken, Victoria's County Court was told.
Judge Sarah Leighfield found the 25-year-old struggled with shame and guilt for what he did as she decided to hand him a sentence lower than the standard term.
She said Teiffel had suffered extra-curial punishment as he continued to mourn the loss of his teen brother and cousin.
He has also been excluded from the Brethren Christian church community he was raised in.
"Exclusion from church and the community has been particularly difficult in circumstances where your entire life has been in that community," she said.
However, she found Teiffel was travelling at excessive speeds in the minutes before the crash.
Teiffel lived with his parents and brother in Wangaratta and his cousins and their parents were visiting when the crash occurred.
On Easter Sunday, April 9 2023, after going to church together in the morning and afternoon, Teiffel wanted to show his two cousins and brother the power of his new Jeep.
He went from travelling 90km/h to speeds of up to 246km/h, in less than 10 minutes.
Teiffel's cousin Arron Suggate, who suffered broken bones in the crash, told the court the speed was the kind that "throws you back in your seat".
After 7pm, as he took the Jeep through a bend Teiffel lost control and the car swiped a tree and then slid sideways into a paddock before hitting a second tree and rolling onto its roof.
Judge Leighfield said Teiffel's behaviour was criminally negligent and the speeds were exceptionally high.
She wanted to send a message to young people to deter them from committing similar offending, as she handed Teiffel a maximum jail term of eight years and nine months.
"If they do drive at excessive speeds, and in the process kill another person or persons, then they will face significant jail time," she said.
Teiffel's supporters cried in court as his sentence was handed down.
He has already served 44 days of his sentence after he asked for his bail to be revoked in July.
