John Boland is said to have suffered a cardiac arrest at the wheel of his Honda following the incident in Paisley, Renfrewshire, in July 2015.
A jury heard how a man confronted Mr Boland in "a rage" after the 60-year-old beeped his horn at him.
Mr Boland later died in hospital. Andrew Friel, 40, from Paisley, denies culpable homicide.
The High Court in Glasgow heard that, at the time of the incident on 8 July 2015, Mr Boland's daughter, Erin, 21, and a 17-year-old passenger were in the car with him.
The 17-year-old told the court they had become aware of a man in the middle of the road.
The witness said: "He was standing in between lanes... John beeped the horn as we had to drive around him to avoid him."
Mr Boland then got caught up in traffic and the man ran up behind the car, the witness said.
He told prosecutor Bernard Ablett: "He slammed both hands on the back windshield, came round to the driver's side and was trying to open the car door."
The teenager said he was "confused and scared" at the time.
He told the court Mr Boland and the man started shouting at each other. Mr Boland then got out of the car before it was claimed the men began pushing one another.
Mr Ablett said: "What mood was the man in?"
The 17-year-old answered: "The only way I can describe is rage. He seemed infuriated."
A passer-by stepped in to try and calm the situation.
The jury heard that Mr Boland eventually got back in his car and the man went off in the opposite direction.
As they drove off, the teenager said Mr Boland developed breathing issues.
He said: "We approached the roundabout and he slumped against the steering wheel.
"We gathered speed and went straight through the roundabout."
The car then hit two fences before coming to a halt.
Mr Boland never recovered and died at the Royal Alexandra Hospital two days later.
Prosecutors allege that Mr Friel approached the car in an "aggressive manner" and shook it. He is also said to have repeatedly pushed Mr Boland and attempted to punch him.
Prosecutors claim that, as a consequence, Mr Boland suffered a cardiac arrest and lost control of the car.
His daughter and the 17-year-old boy are also said to have been injured in the collision.
The trial, before Lord Matthews, continues.
A driver died after an alleged attack by a pedestrian he had to drive around to avoid hitting, a court has heard.