Andrew Thorpe died six days after the collision with the car driven by pensioner John Hodgkiss, on Rotherham Road, Clowne, in the early hours of July 26, 2019.
Hodgkiss, 68, of Barlborough Road, Clowne, denies both murder and the alternative charge of causing death by dangerous driving.
Judge Shaun Smith QC reminded the jury at Derby Crown Court that Mr Thorpe, and his older brother, Nicholas, were returning a trailer to Hodgkiss' home on the night of the tragedy.There had been “bad blood” between the two families for around six weeks after a relationship between Hodgkiss' son, Shane, and their younger sister faltered, the judge said.
When Shane drove past the brothers "looking smug," Mr Thorpe became angry and damaged the trailer in a layby, saying: "He can have it back in pieces."
The court heard that Andrew, aged 32, chased Shane and later kicked the wing mirrors off his car.
Nicholas Thorpe said his brother was in the act of throwing stones at Hodgkiss’ car at the time of the collision.
Describing the incident, he said: “It was like a racing car driver. You could hear the engine over-revving. It didn’t slow down at all.”
The court heard that afterwards, Nicholas Thorpe opened the car door, took the keys off Hodgkiss and punched him several times.
Experts estimated Hodgkiss was travelling at 21-25mph and straddling the central line at the time of the impact.
Hodgkiss later told police he learned the brothers were chasing his son and it sounded as if "they were beating the hell out of him."
He said he became concerned and jumped into his car, turned left on to Rotherham Road and accelerated.
Hodgkiss swerved to avoid one man in the road and "by the time he had done that he saw the other man and it was too late."
"I did not go out intending to kill him last night," he told officers.
A laceration to the back of Andrew's head was caused by him hitting the ground and this led to a "jolting" injury to the brain, consistent with him falling from a car and banging his head.
Home Office pathologist Dr Stuart Hamilton said he would have expected far more serious injuries in a high velocity impact.
In the weeks before the incident, Shane Hodgkiss had intimidated the Thorpe family by performing wheel-spins in his red Mini outside of homes, and had sent a number of messages to the deceased, one stating, “You and your family are going to get wiped out.”
Matters had come to ahead when Amy Thorpe and Shane Hodgkiss had demanded the return of the trailer so they could go on holiday, the court heard.
Judge Smith said the defence described the incident as “fast moving and chaotic” and they argued Hodgkiss is not guilty of either charge.
“You must decide which pieces of evidence are reliable and what conclusions you can draw reasonably,” he said. “You must not engage in guesswork.”
The trial continues.