Suffering a drug-induced psychosis, Rechard Chidi Okonye jumped in a car and repeatedly punched the female driver before screaming: "I am going to kill you".
The woman was so badly injured that she was forced to miss the funeral of her father who had died two days before the terrifying Brisbane attack, District Court heard.
Okonye, 23, entered the woman's vehicle when it slowed in traffic at Milton in January 2021 before punching her head over and over again.
After claiming he was going to kill her, Okonye demanded her handbag before continuing to assault the woman as she tried to call out for help.
She eventually lost control of the vehicle and drove on to the footpath before rolling out of the car with blood running down her face, only to be set upon again by Okonye.
He resumed punching her before she was assisted by passers-by, the court heard.
The woman lost a tooth in the attack, later had to have another removed and suffered a fractured finger that required surgery.
She also has ongoing blurry vision and headaches, the court heard.
"Most of my teeth were smashed, especially my front teeth," she said in a victim impact statement read in court.
"I was also supposed to go to a job interview but I couldn't because of my teeth.
"It is hard to see in my right eye now, all I can see is little black dots. I lost my confidence to go anywhere or talk to my friends."
The woman - who was present in court - later had to make the "devastating" decision to miss her father's funeral because of the attack.
After assaulting the woman, Okonye later attacked a married couple at a Brisbane city apartment building and tried to steal their backpack.
He pushed the woman and told them he was going to shoot them before punching and kicking her husband, who required stitches to his nose.
Okonye had taken a cocktail of drugs with friends the previous night with "catastrophic results" to his mental health, defence barrister Patrick Wilson said.
He was suffering severe psychosis, delusions, and auditory and visual hallucinations during the attacks.
"Before this incident he did not have an inkling of his (mental health) problems that were seemingly bubbling away under the surface and exposed through the intoxication," Mr Wilson said.
"It provides a very clear explanation as to why he did the things that he did that day that were otherwise irrational, nonsensical and terrifying."
His mental health has stabilised thanks to ongoing treatment and medication, the court heard.
Okonye pleaded guilty to seven charges including unlawful entry of vehicle with intent to commit an indictable offence with violence and two counts of assault occasioning bodily harm.
"You are lucky you are not charged with grievous bodily harm," Judge David Kent said.
Okonye was sentenced to three years in jail and will be released in December on a two-and-a-half year parole order.
