Tui Hohepa begged her drunk brother not to get in the car.
The 32-year-old lived with her sibling, Shane Hohepa-Lennane, his fiancee and two others - a couple - in a Hamilton flat.
Hohepa told the Herald her brother had been drinking all day on Wednesday.
When one of the flatmates got home, it was suggested they visit a friend in Cambridge.
There were four people in the car - Hohepa-Lennane, the couple and another man.
Hohepa said she tried to stop her brother from getting in the car.
"That day, I had seen him before he left. We told him not to go, but he was very drunk and very stubborn. Very stubborn. When he was going to do something he was going to do it."
But the car in which Hohepa-Lennane was a rear-seat passenger crashed about 6.45pm on Scott St, near the intersection with Moore St, in Leamington, a suburb of Cambridge.
He died at the scene and the three others were badly injured.
Police allege the driver was over the legal blood alcohol limit.
Hohepa hoped others could learn from what happened.
"Let it be a lesson to others. Everyone has a choice. Do the right thing."
She first heard about the crash when she got a phone call from her flatmate's brother about 8.30pm and went straight to hospital with her brother's fiancee Alisha Eichler.
Hohepa said the female passenger was still battling serious injuries and had many broken
bones. Her partner had at least four operations, but was walking and talking.
The other man had minor injuries but was also hospitalised.
Hohepa said she will always remember her brother as a joker and someone who loved his family dearly.
"He was a quirky kinda cheeky little boy. He liked to crack a joke and put his laugh at the end, 'ha ha ha'," she said.
"My brother was a very simple man. He enjoyed staying home. He loved his PlayStation, definitely loved his beer, he loved his family and loved his sisters more.
"He had a big heart and was always forgiving."
Hohepa-Lennane was one of nine siblings, the fourth eldest and the first-born boy. He was originally from Wellington but he moved to Hamilton about seven years ago to be closer to his family, including his mother and siblings.
Another sister, Ebony Hohepa-Lennane, 30, said the death was still sinking in.
"It still feels like a dream, even though I've seen him [at tangi] it's sort of like an out-of-body experience,"
He was looking forward to marrying his partner in December this year, she said. The couple had been together for about six or seven years and were trying for a child after losing a baby in 2015.
"Shane couldn't wait to be a dad," she said.
There were now a lot of mixed emotions about his death among the family and she expected Monday to be the hardest day when he will be farewelled. Hohepa-Lennane arrived at Hamilton's Hemi Tapu marae on Saturday.
Family had arrived from Wellington, Paeroa, Auckland and Whangarei to pay their respects.
Their parents were taking his death "day by day", Tui Hohepa said.
"With the support of the whanau around here it's not so bad but when everyone leaves and you're kinda like, there by yourself, that's when it really hits."
He left behind his beloved dog, Spartan, a fox terrier-pit bull cross, that was now being looked after by Eichler.
A man faces a number of charges over the incident, including manslaughter and driving with excess breath alcohol.